Hello,
There might be the possibility you need to update any custom templates you have residing in [your-themes]tribe-events/ folder if you’ve got one. I see you checked ‘Yes’ to reverting back to the default WordPress theme and deactivating all plugins other than ours as instructed in the Testing for conflicts guide, but can you please confirm this? It would also help if you could include your System Information as a private reply.
When users have custom templates they are responsible for updating them to match changes made in new releases – of course, we try to minimize disruption as far as possible. Also, we try to clue them in to things they should look for in our Release Notes, and the plugin changelogs, by providing useful data in Events > Help > Recent Template Changes. If you navigate there, you should see a list of recently updated templates (which changes each release).
Try creating a custom template override as explained in our Themer’s Guide. Copy the contents of /the-events-calendar/src/views/month/tooltip.php and replace with the code from this snippet. Save as [your-theme]/tribe-events/month/tooltip.php.
I can’t do more than what I’ve posted above, so best of luck and if you need a visual example of the process, check out this Customizing WordPress #1 – How To Create A Child Theme by LevelUpTutse YouTube video.
Cheers!