Hi @MarcS,
Sorry for the inconvenience caused to you.
We have fixed the issue, and the beta with that fix has been released. It is available to download from here as Enpass v6.6.2. If you try the beta version, please share your feedback with us, or you can wait for the stable version, which will be available soon.
Thanks!
For anyone who does have local admin privs and can install systemwide applications, I got it working using https://www.microsoft.com/en-us/download/confirmation.aspx?id=52685 (x86, not x64).
Obivously not desireable procedure for portable mode, but remember this is beta.