I have had this happening a few times, but never found the reason:
A huge blank space where the pattern editor + matrix was supposed to be.
Now, I finally figured out that it was one of my tools that is causing the visual quirk
If you look at the image below, you’ll see 8 track in a group, which are created on startup, immediately as the song initializes.
Somehow, this causes everything to shift off screen…
(if someone need to look at the tool, send me a PM)