GrabCAD Community User Group

one example is when you try to view file which was modeled in quite new software , newer than GC viewer update. For example file made up with SW 2025 will not be opened. GC need to do some updates from time to time but as you know it is $ problem :)

But those are stl files not a SW files also

It's show problamtic if the viewer didn't render the stl how can other person know what it is and download it (Somehow I managed with adding Image file of the design)

There are multiple reasons this can happen. Sometimes, some files may never render.

The only sure way to have renderings of your models is to create them yourself and upload them. This is always a good idea anyway since you have full control of them and they always show up immediately.