The typical workflow with Alembic is that it is open in another program and you update the Alembic file and then refresh to see the changes.
ZBrush 2021 added Alembic support which is great but if the destination file is in use, ZBrush crashes. Of course it should give proper message about the situation and not crash.
Please fix this soon!
Thanks 
Antti
Hello @anttin
Sorry you’re having some trouble!
Please report any technical issues or repeatable crashing to Pixologic Support. It is the way to get technical attention for your issue from the people who actually develop the program. Directing other users on the community boards to fix it won’t help you.
Good luck!
I tried to find way to report issues but couldn’t, thank you very much!
I will report it there.
Hmm…actually that’s where I was first and then came here as I couldn’t find any report system. So I just start new conversation in Support?
I just did, let’s see if that is the correct procedure
Thank you!