Action bars resetting in instances on frost mage spec only

I have a serious problem which makes my character unplayable.

On my mage and ONLY in frost spec, entering instances (dungeon, raid, pvp, …) is resetting my action bar button allocation.

After HOURS of trying to find out what’s going on I could only find out that entering, leaving and then entering again works but I cannot play the game if I need to do this every time, especially since I would need to do that upon leaving as well because the problem persists that way around as well.

And yes I have deleted all the usual folders and repaired my game… multiple times. It’s only happening on the mage in FROST spec, this HAS to be some server-side issue.

I’m out of ideas and opening a ticket hasn’t been helpful, it was counterproductive as I got a Bot and GM response with the exact same instructions (deleting the usual folders) even though I’ve done that multiple times already. I have no addons, no other modifications, I’m running a completely clean WoW installation.

I am looking for a serious response and permanent resolution to this problem which others are suffering from as well though it seems to be a rare case.

I cannot play the game like this!

i have this sometimes, i go to editmode and back. Then it is ok until i hearth or port somewhere