RSS Feeds within a site.

Created a group calendar in Outlook recently which in turn set up a new site. Decided to use the site & added an RSS feed. Feed worked fine for about a week then suddenly stopped updating. Deleted it and tried to re-add it only to get "Office 365 Connectors relies on groups, and the group for this team site is not yet accessible. If this is a new team site, allow some time for the group setup to complete."

Anyone any idea what went wrong please. New to SharePoint and don't make much use of it but annoying to have something working and then stop.

Thanks.