Thumbnails for custom design elements in MatrixGold

Hi all,
I’m starting to generate some custom profiles in Matrix gold - while they save with no problems (I am able to open them and use them in a design), I can’t see the thumbnail of them; it just looks like the rhino logo. The same happens when I choose a saved file to be the master file. Screenshots are attached. I’m running the newest version of both Rhino and Matrix - I tried running the “repair” function for Rhino from the control panel but that didn’t work. Any ideas? Thanks in advance