I've had this happen in the past (prior to Hist dropping) but things have been better for a while. Couple of things I noticed and have done that I picked up on over a little testing:
- This only happened to me when I launched ESO direct from the ESO app rather than through the launcher. I also had some missing textures as well. Always playing via the launcher improved things no end.....yes, no logic to it, but it worked.
- I've also noticed on a few occasions in my settlings file (usersettings.txt) that the LUA Memory line had changed from my manual settings of 1024 to 0. This suggests that all memory allocation for add-ons MAY have been removed. Changing it back to my setting and locking the file stopped this.
On the last issue (LUA memory) I'd love @chris.dillman to confirm whether this is normal following the move to the 64 bit client (It may be a setting to allow 'unlimited' memory to AO's) or whether this is as a result of a bug.