The issue will be resolved by Synology in a future update.
You can solve it yourself by going to the folder where enpass is on the Nas,
1 to choose for editing
2 go to NFS Permissions
3 if under Action the line Convert to Windows ACL is clearly readable, you have to click it. Then this command will be executed and the problem will be solved.
That has worked for me!
Everyone does so at their own risk! I am not responsable!
I submitted a problem report to Synology through my account and this was given as a solution.