Hello,
For me, I have found the solution. It is a problem where IIS does not serve the .enpassdbsync file correctly. To fix this issue, you need to go to add a MIME type under your webdav website in IIS. The extension should be .enpassdbsync and the extension text/plain. Enpass should receive the file correctly and be able to add or find the required encrypted text correctly so the sync can occur. Screenshot