I manually checked all addons and couldn't figure out which one it was but after going through (and enabling) them all I now am suddenly able to use abilities/items/etc in the quest tracker.

1x [ADDON_ACTION_FORBIDDEN] AddOn 'HandyNotes_BattleForAzerothTreasures' tried to call the protected function 'CastSpellByID()'.
[string "@!BugGrabber\BugGrabber.lua"]:519: in function <!BugGrabber\BugGrabber.lua:519>
[string "=[C]"]: in function `CastSpellByID'
[string "@Blizzard_ObjectiveTracker\Blizzard_ScenarioObjectiveTracker.lua"]:661: in function <...jectiveTracker\Blizzard_ScenarioObjectiveTracker.lua:660>

I have the same problem.
Got this error EVERY TIME i try to use an quest item from the quest tracker on the screen. Cause of this i can't use quest items from the tracker with this addon enabled.

HandyNotes_BattleForAzerothTreasures forbidden from using UseQuestLogSpecialItem() (Only usable by Blizzard)
Count: 42

Call Stack:
[string "=[C]"]: in function `UseQuestLogSpecialItem'
[string "@Blizzard_ObjectiveTracker\Blizzard_ObjectiveTrackerShared.lua"]:95: in function <...ObjectiveTracker\Blizzard_ObjectiveTrackerShared.lua:88>