You should try starting a new game and see if your problem persist. I've never experienced that issue in my TIE game-time before but it's possible that something in your save-game might be breaking it.
Sculelos, since your suggestion sounded reasonable, I went ahead and started a new game. Once again, newer versions of TIE would allow guards to track me when I was 'invisible' while older versions did not have this flaw.
Per the request from Arthmoor, I was able to narrow down the issue to TIE v.1.26. TIE v.1.25 works fine (it is 3,776 kb) while TIE v1.26 does not (it is 4,832 kb). Shall I post the older versions on tesnexus for your review? Also, FYI, here are notes from TIE v1.26:
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Changes made to Version 1.26
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There is a lot of ground to cover here. First off, over 200 new NPCs have been addeed to the game,
bringing TIE up to a respectable 800 plus NPC total. Most of these are Nobles and prisoners - along with
a few Inn guests.
Besides the new NPCs, there's also the tougher prison escapes to have fun with. I won't spoil the
surprise for you, but expect a much greater challenge now when breaking free.
Fences are tougher to seek out. They only frequent certain Inns now, and only buy and sell at night.
Find out where they are by visiting the Anvil secret hideout. Want to find the hideout? Look hard
in the dungeon tutorial - especially towards the end by the exit.
Fighters can now enjoy tougher battles in TIE - as long as they use a shield. Almost all shields
in the game have been improved and toughened. As long as players use their wits and fight with
intelligence, they can survive even the toughest foes. Of course, that depends on how high their
Block skills are too.
Secret entrances have been tweaked. Enjoy.
Morerunes has blessed us with a way to pay off existing bounties and fines - without forcing the
player to join a guild. Again, the clue to finding out how to do this is within the Anvil lair.
Arthmoor has pulled it off again - giving us OpenCities and Better Cities compatibility. I'm
going to have to try those mods out myself. I've heard so many great things about them.
Castles, Fighter Guilds, and mage halls have slightly more "interesting" loot prospects in them -
along with keys you'll need to find in order to access them.
Health and fatigue potions as well as spells now work slowly over time instead of instantaneously.
That really bugged me from the start.
Look, there's more, but I want you to experience TIE's fun and immersion in the game rather then
in a ReadMe. So please go forth and enjoy this exciting new version of the Tamriel Immersion
Experience. It's been a blast to create and I don't foresee not performing regular updates from here on.
Of course, any work done on it will be more for Shivering Isles than Tamriel...