Hi Danielkop,
Let’s work to get those calendar events saved on your Mac in the Calendar app, instead of defaulting back to ‘New Event’.
Do you sync your calendars with any accounts? If so, does it happen with all accounts? You can check this in Calendar > Accounts. You’ll see a list of accounts on your left and then you can click on them and determine which account has Calendars enabled.
Do the events from your iPhone appear in Calendars on your Mac? Again, this would be the product of a sync through an account but would let us know that the sync process is completing. Do any of the ‘New Event’ events show up on your iPhone?
If you are syncing your calendars, we’d like to have you turn off Calendars for all your accounts, again from Calendars > Accounts by clicking on each account and uncheck Calendars. Then try adding an event, does the same thing happen?
We’re eager to get those results as we start isolating the situation.
Thanks.