Ok, I experienced the weirdest bug today. I will recheck after server reset and report if it seems to have fixed itself.
PC: Iim'mur'ss, Drow, Light sensitivity, Night Eyes, Custom Feat: Shadow Augment, True Seeing (all were active)
Area: Benwick Hollow: Shrine of Eilistraee
Effect: While standing around the exterior of the Shrine of Eilistraee, each time Iim's True Seeing expired, I would get a server message that said "attempting to resist spell", "Spell Resisted", then the Light Sensitivity notice. AND THEN... she'd turn invisible! I couldn't dispell these effects using the rest menu. I could rest and it seemed to go away. After about the third time I relogged to see if it would fix. I stopped getting the effect, but then I went to Wharftown. Aedan couldn't see my PC even though she was not Invis and not in stealth, though Rith'tar and Valerius saw her fine. (might not be related, but seemed odd with everything else).
Once before leaving the Shrine I got a notice that I couldn't rest for another 0 minutes. I didn't think anything about it. But then... 3 hours and 20 minutes after the last time I had rested, it happened again! It said I had to wait 0 minutes, and canceled the rest. I immediately hit rest again and it worked.
Before all of this started, I had cast darkness for a screenshot. That's the only thing I can think of that might have set this chain off... or there's a bug in a script somewhere.