To elaborate, you may have no addon that directly interacts with the castbar but the addon itself may be outdated (therefore corrupt as Perl said) or have several conflicting issues with multiple addons. Since you said it happened after the 6th June update this is very likely.
If you still have the same problem with a clean reset (no addons) then its a native issue, but if you don’t then you’ll have to re-enable addons one by one after that to see which one is interfering and try to (wait for an) addon update or keep it disabled/replaced for another.