Could you try the new upload I added, “premium_nano4x_v1-0-0_64_raspi.zip”? If this works I’d appreciate knowing as I might need to go back and recompile a lot of my older games.
I checked through some of the build notes and it wasn’t until later versions that Pico8 supported 64bit, which the original builds were done beforehand. I’m hoping this fixes your specific problem.