System: Ubuntu 16.04.3 LTS, i did install owncloud from the repo
deb http://download.owncloud.org/download/repositories/production/Ubuntu_16.04/ /
I've had a strange problem since we switched to version 10. x.
Among other things, we use OC as a calendar server. As a client we use, besides IOS, Lightning under Thunderbird.
On version 8. x everything worked as expected.
On version 10. x there is no longer the function "Invite participants". The checkbox is checked, but grayed out. And the invited participant does not receive an invitation.
It's probably no problem with Thunderbird. If I set up a local calendar for testing purposes, I can invite participants into appointments there. It just seems to be a problem with oc.
When I use the webfrontend to create appointments, I can invite participants there to see what works.