MS4 - Palette symbols suddenly disappears after use

Having a symbol issue in MS4. This was a problem in MS3.6 as well, but I haven't reported it before now. Some symbols randomly disappears from the palette folders after using them once, and won't reappear before restarting the app. They aren't just invisible, as they can't be selected and used either, but they act as spacers in the palette folder instead of a symbol. It happens randomly after using them, maybe one or two symbols during about a half hour session, and it seems to not be connected to any specific symbols but can happen to any of them. When restarting, it shows up where it's supposed to. Not sure what to do here. Is this the correct place to submit bugs or is there a GitHub or another page more appropriate?