MacOS Calendar issue My Calendar app is configured to read more than one calendar (iCloud, Google, Exchange). If I create an event from my computer, it won't be visible on all other calendars, and if I create an event on any of my iOS devices I cannot see on the Mac Desktop Calendar. 

I tried to remove Calendar from iCloud Settings on my Mac but, I did not get any luck.
First, check your iPhone:

For iCloud Calendar, check whether it is enabled on both devices under Settings &gt; Apple ID &gt; iCloud

For Google, check whether Fetch New Data is set to Push in Settings &gt; Passwords and Accounts and also  under Gmail look, whether is it enabled or not.

For Exchange try the same.

Now check the same settings on your mac.