Hi Anshu,
Thank you for your quick reply. I installed the beta version yesterday, and this morning the problem was different.
Instead of the "sync forever" problem, I know have a "Fail sync" problem (with double red arrows, similarly to bastischubert). The error message is only "There went something wrong while synchronising. (Error code: -119)".
As before, restarting Enpass fixed the problem (for today).
(Also similarly to bastischubert, I have no problem synchronizing with my android app.)