Hi Vikram, thanks for coming back to me.
Your test definitely worked out, I still see your testing files.
I updated the iOS App to 6.0.4 (222). After I configure the WebDav sync it behaves like everything works and prints a "Last sync" datetime. Having a look on my server shows me no new files. Next sync process Enpass says "no files found, looks like you deleted them. Click Next to upload now"... I can repeat this as often as desired.
btw: How did you format the URL? I'm using: https://sub.domain.tld:port/path/
Edit: 908401, again. I can't reproduce the above discribed behaviour.
Edit2: Resolved - I tried with the demo access I provided to you and it worked. Turns out enpass can't handle the Synology option "Hide sub folders for users with no access right".......