I did get another crash, but it took a bit longer to occur. Again, I was just clicking around different objects in the project edit window. Since I was clicking around so quickly, I can’t remember exactly what I was doing when it happened. I think I was clicking around in the project footer area. The full crash data is attached below and looks similar to the previous crash data that I posted.
Hope this helps. When you come out with another beta, I’ll continue testing. Btw, I know M1 Big Sur has a number of issues with my other apps too. Maybe some of these issues are with the Apple software. Hopefully Apple will soon come out with another system update and some of these problems (including Blocs) will go away.
Have a good weekend! 
pruthe
Blocs-M1-crash-01-09-21.txt.zip (31.5 KB)