Model group missing

Hi all, as the season is over i am playing around in xLights 2023.22 on Windows. I currently have a situation where 2 Model Groups have disappeared from my layout but there are still models as part of that group. I can’t rename a new one to the same name or remove these models from that Model Group. These groups still show up in Sequencer and i can add and remove them in Display Elements and they can still be sequenced. Any advice is much appreciated!!

SOLVED - thanks to BAZMick. Those 2 Model Groups had ended up being set as Unassigned under Preview. And that drop down box on the RHS for selecting Preview disappears if the Models window is to large. Took me a bit to figure that out.

Had the same problem , only way I could fix it was to edit the xml file