Hello TaloAC,
I'm Diane, an Office Apps & Services MVP specializing in Outlook, and I’m happy to help you today.
Did you subscribe to ics files or open them as shared folders?
There is a delay of up to an hour for subscribed ics files. There should be no delay if they are opened as shared calendars, especially in outlook on the web. In Outlook on pc, if you are caching shared folders, the cache might need cleared.