I have the same problem now for months. With the help from the findings in this thread I just found that while Enpass freezes it writes the Backup. My Backup is 93MB and on a NAS in my Network. To write it, it takes about 4 minutes. And during this time Enpass is completely frozen.
Why does this takes so long? Copying the same File to the same share directly, it takes only seconds - so it is not a network issue.
More important: Why does Enpass freezes while creating the Backup?