I found a bug that was in v1.00.2, so I'm not sure if it was fixed in v1.00.3 (about to play it now), but in Sigma 1, if you beat Stellar Primate and go back up into the boss arena, you can trigger what I'm guessing is the transition animation (where X runs to his spot after you have made it through the door). If you go completely to the left X will turn and run the to right, fall to the next area and you'll be locked in place. You can't pause the game at all, you can move, you're just stuck until you force the game closed.
I'm playing on a Windows 11 desktop, but I figure this may be an issue across all platforms.