If you have a VRayLight Plane with softbox texture enabled, then change the light to a sphere it won’t work (even though texture is greyed out). Not a big deal.
Softbox textures in max 2012 don’t work well in the material editors - slate is especially bad. With the classic mat editor I have to click a non-softbox slot, then back to get updates.
I did a few tests with 2.40.03 and 2.40.04 on Max 2012 and I could say that I didn’t get any issues with VraySoftbox update in both Compact or Slate Material editors.
Would it be possible to update to the latests official 2.40.04 build and let us know if the issue still persists.