I originally installed Enpass on a Macintosh using version 5 and had created a password list of 63 items. After a week or so I was prompted to upgrade to the "new" and "improved" version 6 but declined and still use version 5.6.11.
I decided to give it a try on Windows 10 and downloaded what is the latest version on the Enpass website, Version 6.something. After installing and opting to sync to the same DropBox database created on the Mac, it only synced 58 items. I did a couple more attempts at resyncing and still it did not bring over the full number of items.
The fix was for me to uninstall Version 6 on WIndows and download an older version for Windows 10, Version 5.6.10. After installation and a sync, all the items on the Mac side now show up on the Windows side.
I will not upgrade to version 6 on either platform after experiencing this...it is buggy on Windows and may also be so on the Mac side.