It could also be a corrupted file. Try opening the .BPN file with the same name to see if you get the same problem. Hopefully you have your preferences set to save a backup as this has saved my bacon a couple of times with corrupted files.
Cheers,
Gerald
Gerald Hoffman
“The simplification of anything is always sensational” GKC
Archicad 4.55 - 27-6000 USA
2019 MacBook Pro-macOS 15.0 (64GB w/ AMD Radeon Pro 5600M GPU)