Working for me, most of the time works, but has happened in the past.
Go to iCloud.com and see if the events are there.
If so, disable Calendars in iCloud on the iPad, then re-enable. Might just be “stuck”.
If that does not work, sign-out of iCloud and re-sign in on iPad.
If not seeing event in iCloud, it’s iPhone side so do above but on iPhone.