So this is what happens:

I have an NPC with an Escort package that kicks in when a global variable changes from 0 to 1. This happens through a dialogue choice.
So basically you come up to him, you choose the right response and he leads you to a certain location.

Okay, everything works great. If I start up the game, load up any save I have, COC to where he is, and choose the response he sets off on his Escort.
But if I load up another save after this and do the exact same thing, he just stands there as if there was no Escort package.
Even if I load up the exact same save as before, do the exact same things, the second time around he just stands there.

The only condition on the package is the global variable. I've tried it with items, with quest stages - same thing. He'll respond the first time around, but if I load up any save game after and try the same thing, he doesn't respond.

Has anyone had anything like this happen before?

Ya, I know that issue all too well...

Let me guess, you are loading a save without exiting the game, right? If you actually exit the game and then restart the game and load the save, it will work, yes? If this is occurring in an area that you made yourself, then this is the infamous navmesh pathing bug that plagues ESP files. The only way to correct this is to turn your mod into an ESM. This bug manifests with certain shapes of navmeshes where the navmesh loops around behind itself somewhere in the cell. Most of us just live with the issue until release time as once you turn your mod into an ESM, you can't edit it anymore.

Sorta yeah...

one can of course swap back and forth between .esm and .esp as necessary (be aware its an FO3Edit adjustment to internal flags to do this, not just a file rename). For short testing sessions I use stuff as .esp and then I might FO3MasterUpdate the mod list for longer sessions where I know I could have reloads and so on,

Strangely, I tried the ESM solution and discovered that my packages started behaving even worse after that. Mostly my NPCs would just stand around, staring at walls. Converting back to an ESP got them moving again. I didn't test this extensively, but it was enough to discourage me even attempting to rely on the ESM fix.

pkleiss, your description of the problem is the first and best I've seen. It really clarified it for me, and makes me think I may need to give it a shot again, at least when I release my mod.

Very strange.

I did have one case where FO3MasterUpdating a file broke an exterior navmesh edit within Point Lookout. It was not a complete failure of the navmesh but an inability to cross the cell border into the adjacent cell, even though the navmesh was finalized. I ended up moving the navmesh into a seperate .esm file and it seemed to work that way.

I've never heard of esm'ifying a player-created interior cell causing a failure.

Ahhh, well my strangeness was all in an exterior. The wasteland worldspace to be precise.

Wow, I'm glad I asked, never would've figured that out myself
Yes, that's exactly the issue.

In that case, two follow-up questions:

1. Is it worth trying to simply re-create the navmesh or is it a "deeper" problem with the cell now?
2. Could someone point me to where I could find out how to turn ESPs into ESMs?

Thanks.

1) Recreating the navmesh won't make the problem go away. The problem lies in the actual shape of the navmesh. Recreating a navmesh of the same shape will make the problem re-occur. You would have to change the cell structure such that there are no looping navmesh paths.

2) http://www.fallout3nexus.com/downloads/file.php?id=637 can change your ESP into an ESM by loading your mod into FO3Edit and then editing the 'Header Record' and checking the 'ESM' flag in that record. I understand that FO3Pluggin can do it too, but I have never used that tool.

http://www.gamesas.com/index.php?/topic/1032946-navmesh-processing-in-esp-files-still-has-a-problem/page__hl__navmesh (its a biggie, but the resolution comes at the end of that thread).

>>FO3Pluggin can do it too, but I have never used that tool.<<
Fallout Mod Manager FOMM can also toggle The Flag in there for much faster time than waiting for FO3 Edit to load all its stuff.

The ONLY thing FO3edit is changing in this regard, esp to esm, is the one checkbox for the flag ESM flag, correct ?...i.e. its not making some other changes that the other programs are not?

Ya, that's right. It doesn't change the filename either. You end up with an ESM that has an .esp extension, commonly referred to as a 'false ESM'.

Just to clarify, this is happening in an area you made yourself, yes? With a custom navmesh? If so, then this is an old problem. The game is not recognizing your new navmesh, thereby causing NPCs to ignore it. This results in them being "frozen" in place. For me, my NPCs would freeze up after I fast traveled back to the location, or if I waited an hour or more. You need to:

1) Find the FormID of your new navmesh
2) Load up your esp in FO3edit
3) Change the navmesh's formid to a custom number, for example 00630211
4) Add something in your game to enable the navmesh (trigger, object with a script on it). Use this line: "EnableNavmesh 00630211"
5) Save your esp as an esm. I recommend FO3plugin for this. All you need to do is load the esp, and then save as an esm. Very easy.

The NPCs should behave normally after that.

If you do ESMify your plug-in, then I would recommend always using the same program to master/unmaster it. I used both FO3 and FOMM to do that once and ended up with a totally buggered file that I had to dump and revert to a back up file to cure. These days if I want to test my mod as an esm I will make a copy of my file and master it to see how it functions, then go back to the original esp file for continued editing if necessary. I think that may be overly cautious compared to mastering and unmastering the same file, but the one experience soured me. I hate losing several days work.

Mastering my file seemed to stop NPCs from losing their AI packages when I fast travel away and back, or load a savegame, but I still have trouble with some NPCs losing their AI packages if they move from an interior cell to an exterior cell during the package in that event. Anyone know of solutions to that? Does scripting a navmesh enable command resolve that?

I use FO3MasterUpdate and FO3MasterRestore to change my mod. I have done it many many times without any problems so far. As for using a navmesh enable function to make the pathing bug disappear in an ESP, I'd like to hear some others confirm that this does indeed work. That would be awesome.

Well, I'm glad I looked back in on this thread. Thanks for that very detailed little tidbit of information Azar. It is an area I made myself, in a Wasteland World cell, with a custom navmesh (well, thirty or so spread over 10 cells).

I am going to try what you suggest, prior to release. As I have many, many navmeshes, it might be a little more work to set up. If it works, it will be well worth it though. Currently though, I am just using an .esp and things are working fairly smoothly. However, like Badpenny, I sometimes notice the odd NPC standing like a zombie. Occasionally several in a certain area. For now. I am going to bookmark this thread for when the time comes. Then I will experiment with solving this issue, and see what I can come up with. Hopefully your suggestion does the trick.