Ok, as posted before when working with version 5.20, I experience a simular problem:
In v5.20 suddenly the Plane manager-dialog wouldn't open. Not through the icon in the ribbon, not via selecting "new layer" in the Cutting Plane View... So, I've upgraded to v5.30.
In v5.30 the Plane manager-dialog did function again, but now I can't open the Layer manager-dialog. Not through the icon in the ribbon, not via selecting "new layer" in whatever dropdown-menu I can find. In the latter, I constantly get new layers like 'new layer 1", "new layer 2", etc. But I can't rename them, I can't import a layerset, I can't change linestyle, colour, etc.
Is it just me, or doesn't TBC remeber your setup on restart? Frequently I have to reopen the View Filter Manager.