I checked all the items you list and none of them are a factor.
Does it have anything to do with the fact that I am the administrator/creator of the Team?
The reason I ask .... I created a test profile/person in my team - Suzy Q.
I created 3 events with reminders that should have been emailed to myself and to Suzy. Suzy got all 3 email reminders but I did not get any.
Then I signed on as Suzy and created 3 events with reminders that should have come to myself and to Suzy - and they did! So in Suzy's email she got 6 reminders - 3 of mine and 3 of hers, but in my email I only get the 3 that "Suzy" created.
So it worked when I was signed into the system as Suzy but it did not work when I was signed on as me.
??