My browser / operating system: MacOS Macintosh X 10.15.7, Safari 14.0.3, No Flash version detected
The online editor works just fine, but the offline editor can only program and cannot properly run code. When I do run code, it just shows the variables and a blue screen. It doesn't even show the backdrop. The problem is only in the offline editor. I restart it and the bug is still there. I restart my computer and it's also there. Pen also doesn't work. Here's the image:

maybe I hav to reinstall it

got it working after reinstalling twice (once from App Store, fail; once from official download page, success) so imma close this topic