Good Question Harri...I've been battling this one too. My issue occurred after I published project, went to home page(my projects), then tried to open the project again. I've closed Thingworx app and restarted computer with no luck of getting it back. I can go to the preview and it shows the 3d information correctly..so guessing it is just some graphics issue in Canvas window because the information is there. I've included my graphics information at bottom.
Strange...I come back 6 hours later and open the project with success to see the model in the canvas. I did have to re-login to the VES...this may be what is needed to see the Canvas???
Harri, I'd be interested to know what you mean by "everything". I temporarily renamed the user data folder as you have noted to enable creation of a new folder, but it didn't repair for me. After doing this, now I'm unable to see the 3D information in my preview window where before I was able to...so I'm really going backwards.