I have found same bug. The action bar did disappear. If you save the game and load the game the bar is back. Same problem with DX11 and Vulcan so most likely not GPU based.
I was fighting in the beach near the druid place in atc 1, the last character in the character column was Lae´zel and it was always her whose action panel did disappear. In Steam forum several people have had same problem with Lae`zel and in different encounters, so it seems to be related to her?
But in anyway save file most likely does not help, because loading the save file did fix the problem. Did hapen twice in my encounter...
