I have the same problem as my phone no longer syncs with the desktop and vice-versa. Enpass 6 on desktop and Enpass 5 on Windows 10 mobile (Lumia 950XL) and no way to upgrade as Enpass for Windows 10 Mobile has been pulled from Microsoft Store. Hugely disappointed at being left in the lurch with no warning after having paid for the app!
When Enpass UWP is opened in the connected display via Windows 10 Continuum, the settings page is non-functional. Clicking on any of the menu options does nothing.