A full hybrid was recently set up on exchange 2013. When some mailboxes were moved to the cloud after the hybrid was set up, there was an issue of viewing free / busy information for the user that was moved to O365. MS support asked that the autodiscover be pointed to O365 instead of on-prem (only a couple of users in O365 and rest are on premise). When that was done the free / busy was visible for the user in cloud. However, right after the move some users that had the mapped the cloud user's calendar to their outlook received an error that the admin had made some changes which required restart of outlook. Thereafter, it has been prompting them for credential whenever they try to access their calendar (which also contains the mapped calendar of the cloud user). Also, one of the users on premise that have the cloud user's calendar mapped is not able to view the on-premise users calendars anymore. The user had a few users' calendar listed under shared whose contents were visible. However, that is not the case anymore.
Any insight would be appreciated!