hi anthony,
are you a global admin of your office 365 organization? can you use the exchange online windows powershell? if so, please try using the exchange online powershell to fix the issue. below are the detailed steps:
1. connect to exchange online using remote powershell.
2. run the command:
add-mailboxfolderpermission -identity *** Email address is removed for privacy ***:\calendar -user *** Email address is removed for privacy *** -accessrights editor
if you receive the following error message when running the above command, please run another command:
set-mailboxfolderpermission -identity *** Email address is removed for privacy ***:\calendar -user *** Email address is removed for privacy *** -accessrights editor
if the issue persists after running the powershell commands above, to narrow down the issue, i’d like to confirm some information:
1. how many users in your organization encountered the same issue?
2. if you are an admin of your organization, could you please tell us which office 365 plan you are using, business plan or enterprise plan?
3. did this issue happen both in the outlook web app and outlook client (e.g. outlook 2013, 2016) when user2 attempts to open the calendar of user1?
4. are you using outlook for mac client (e.g. outlook for mac 2011, 2016) or outlook for windows client (e.g. outlook 2013, outlook 2016)?
if you don’t know how to use exchange online powershell, please feel free to post back so that we can offer you some guidance.
thanks,
mouran
