… or to start a free trial? 
just out of the blue: all was fine, yesterday, after updating from 1.4 then…
not an issue though: just re-entered my login and I’m up again with everything (library and devices) still as it was
EDIT: oh, wait… might it be because I updated my Mac mini’s OS (where Roon Server runs), from 10.11 to 10.13?