at the moment, it seems to be impossible for ordinary members to leave groups; there seem to be 2 ways that they should be able to do this - which work when i am logged in as a magnetic; but any other log-ins just lead to the "lost?" page.
one path is:
Network > groups > My groups > edit membership
(e.g. for the Norway group, when i'm logged in as me i get to /en/og/manage/815?destination=og%2Fmy which tells me i can't leave because i'm an owner of the group. when i'm logged in as test-auth i get to /en/og/manage/54?destination=og%2Fmy which is the "lost" page, & when i try logged in as admin i get /en/og/manage/815?destination=og%2Fmy which is also the lost page)
another path is:
Magdalena Norway > contribute > My membership
(logged in as me i get to /en/og/manage/815, telling me i can't leave because i'm the owner; logged in as test-auth i get to /en/og/manage/815 & it is the "lost" page; logged in as admin, i get the same).
since it works for magnetics, i have spent some time hunting through the permissions to see whether it is that, but couldn't find anything relevant; then i've gone thru all of the OG configuration, also found nothing relevant. then i've trawled through the pretty sparse documentation & the only thing that suggests it could be is some kind of block ... but i can't work out from looking at the blocks what it could be.
it's a mystery but it's one we really need to solve!!