Howdy kwirxcreative,
Thank you for reporting this and taking the time to research it.
One thing I want to clarify, choosing all events updates that event and all future occurrences. So, past occurrences of the event will not be updated. The best way around this is to update the first event of the series to truly update all events.
Assuming you already knew all of what I just explained, my primary suspicion would be that a caching plugin is interfering with your update. How our plugin is designed is that all of those events will share the same database entry. If the events you have edited still share the same URL, and do not have like a -2 or something after the event title, then you are looking at the same event from the database. It would definitely take another plugin or theme to be interfering and cause the content not to change, almost definitely some sort of caching plugin.
Does that make sense? Please let me know. Cheers!
– Brook