Calendar Alerts keep changing on shared calendars

I have multiple calendars I share between work and home. They all have the SAME SETTINGS: regular events have default 30 minute alerts. All day events are default 9am day of event.

BUT, when I change an event on my home computer, even if I CHANGE the alert to 9am for that day, when it syncs with my work computer it changes the event to alerting at 12am day of event, and says that that was the default on my home computer. NOT TRUE!!!

How do I make the events default to the DEFAULT time? Why is this happening? It's so annoying.