Use the screenshot trick ingame to find out where exactly ESO thinks your addons must be!
It is described here:
https://www.esoui.com/forums/showthread.php?t=8858
-> "In addition you can login, take a screenshot via they screenshot keybind and watch the text written at the top right corner of the screen."
Sometimes Windows patches or OneDrive disable/enable makes ESO go mad about it's live/AddOns folder.
All of sudden it is not anymore in c:\users\...\document\Elder Scrolls Online but c:\users\...\AppData\local or whatever
And I have not found out yet how to fix ESO to use the correct folder again
What you need to do after you find out which folder the screenshot shows you:
Move your addons into the folder AddOns (1 level above the /Screenshots folder) and update them there, as ESO will only search in there now
Same for your SavedVariables! Copy them over there too).
e.g. if the screenshot shows you your exected ESO folder for addons etc. now is
c:\users\...\whatever\Screenshots
You need to copy the files and folders from your old ESO folder
c:\users\...\documents\Elder Scrolls Online\live
(e.g. /AddOns and /SavedVariables and the files UserSettings.txt and AddOnSettings.txt) there.