inbox sync pending when subscribed to public folders

Hi team,

I've got 3 end users in our environment that are having a similar issue.  Whenever they subscribe to the public calendars that I create in the O365 admin portal, their email inbox status goes to "sync pending" and no email comes through.  The only way to resolve it is to close out of Outlook and reopen it and then all the email comes down. Can you help?