Hello!
Sorry you have encountered this issue. We are investigating it. Can you send your dump files to us so we can have more information about what went wrong? You can find the steps here:
Meanwhile, it seems that your save file is completely corrupted. Since you mentioned the place has been published, you can probably open it from the published place instead. Or reverting to a previous version.
I am also experiencing the same issue. I tried cloning the file, checking for .LOCK file, etc to no avail.
Only way to open files is to launch a new instance of studio, (ie opening the exe file) and opening a place from there. Opening a place from within another place does not work for me.