We have a full hybrid setup.
An on premise user is trying to send calendar sharing invites to EXO users.
The Exchange online users with 365 apps for enterprise cannot accept the invites they get an error:
"There was a problem connecting you to the shared calendar"
If the same user uses Outlook 2016 to accept the invite it works and they can view the calendar back on their 365 apps.
Im wondering if there is some setting/registry entry for the 365 apps for enterprise that could allow them to accept the calendar invites.