The pattern viewer is very very very old. It may not work under the newer operating systems anymore.
If you want to try, I suggest to uninstall and then re-install the software.
Note - I've had two different products (not PCStitch) where the .exe file for the product was removed during a windows update. No one has ever been able to tell me what happened.
hmmm..I wouldn't think it was old for me because I just downloaded it in Feb 2025. I had to get a new laptop Windows11, and my old PCStitch10 wasn't working well, so I just upgraded to the PCStitch 11 in Feb 2025 and that was when I got the Pattern Viewer as well. But really wasn't sure what the pattern veiwer was for, as before I never used anything like that with the old version of PCStitch, so this was first time clicking on it, since I could view my saved patterns in 11, I clicked on the viewer and got nothing to pull up. I guess maybe I need to uninstall both of them and reinstall. Thanks
Pattern Viewer cannot modify any pattern. It is just that - a pattern viewer. I don't think it's been updated since PCStitch 8. If that's the case, it's possible that the patterns you are trying to view with it are just not compatible.