[Cobberman]

Just upgraded to Maxwell | Sketchup V4. When editing a .mxm material file and saving the file the folder level thumbnail changes from whichever preview scene I was using (ie simball) to a generic filetype thumbnail (green Maxwell logo with ME over it) and doesn't save the preview image.

[Asmithey]

This will sound strange and I have no better explanation. But I have experienced this, more than once, and I pinned it down to a corrupt material. Once I deleted the corrupt material, all the material icons were normal again.

[3DM]

I don't use SU, but have you tried to do an interactive preview render before saving. Make sure it is set to CPU mode though and try it with the perspective camera active. It may also work with an added camera, but see how you go.

Edit: scrap that I was thinking of scene files in the library, not MXM's...apologies.

[JDHill]

Just upgraded to Maxwell | Sketchup V4. When editing a .mxm material file and saving the file the folder level thumbnail changes from whichever preview scene I was using (ie simball) to a generic filetype thumbnail (green Maxwell logo with ME over it) and doesn't save the preview image.

This is because the thumbnails shell extension is something previously installed by Maxwell itself; I'll make sure to include the installer in the next plugin installer build (similar to the way the license manager installer is included).