I've hit a snag in the Dawnguard main quest "A New Order". I apparently cleared the radiant quest location for Gunmar before getting the quest and now he enters the cave and stands facing a wall.

I've already tried adding the Unofficial Dawnguard Patch and it didn't help. Anybody got any ideas?

Hmm. If you had a save from before clearing that cave, that would be the best thing, if it didn't mean erasing too much progress.

Do you have a save from after clearing the cave, but before talking to Gunmar? If so, load it up and try waiting 10 ingame days so the bears can respawn.

Or, after installing the UDGP, try making a game save and immediately loading that save in order to "kick" the new scripting into action. Sometimes the new scripting has to be baked into your save before it will do anything.

If all that fails, leave the cave, and try the console:

setstage DLC1HunterBaseIntro 70

And then travel to Fort Dawnguard. If Gunmar and Sorine are in the main foyer and the quest advances properly, then you should be good to go.

I would test the console command out for you if I could, but I don't have a save file that's at all convenient for doing so. Using the console to get past a scripting glitch is risky, so make sure you have saves to revert back to if the result is messy. Sometimes it is.

Hope that helped.