I am new to this forum and a Zimbra-FOSS-Admin on a Zimbra 7.2.4 in production and 8.0.4 in testing environments.

On our productive server, I upgraded from 7.1.x to 7.2.x and lately to 7.2.4.
Somewhere in this update chain (for sure at 7.2.3), adding attendees on iPhone/iPad was not possible anymore – no invitation button at all.
On the Zimbra-Web-GUI and Apple Calendar client, everything works as expected.

Same thing on a freshly installed Zimbra 8.0.4 version. Either with default COS settings or with enabled iCal delegation.

Does anybody know any workaround this behavior?

Could well be an Apple issue, but (free) calendars on iCloud or Google work flawlessly with invitation/delegation a.s.o.

Regards, Daniel