Calendar not syncing in All Deivces and in O365 OWA

Currently my calendars in all my Apple devices (iMac, Macbook Pro, iPad) and my android phone is not syncing to each other including the O365 OWA.

The calendar I uses is iCal and Macmail

Steps that I have tried and checked:

Removing my account and adding back in.

Check to make sure that my icloud is not sync to my iCal.

The strange part is when I log into my O365 OWA and change the event in the calendar it pushes to all the devices but when I change the event on regardless of which apple device and android, it doesn't get sync.

any suggestion?

thank you,

AppleO365