Maintenance for the week of March 16:
• [COMPLETE] ESO Store and Account System for maintenance – March 18, 6:00AM EDT (10:00 UTC) - 4:00PM EDT (20:00 UTC)
well i don't know if that's it since you didn't go into much detail but after the recent patch and API change many addons stopped working. The one you are refering to is last updated in february so...that might be it.
I'm guessing it has to do with how they changed the bags/backpack/bank functions because of the double bank size for subscribers. Don't know for sure though, since I don't code.