Could you please share a screenshot of your flow's configuration?
Do you create your flows using the "Create new events on Google calendar from Office 365" built-in template and the "Google calendar to Office 365 calendar" built-in template?
I have made a test on my side and don't have the issue that you mentioned. My flow's configuration as below:
Outlook Calendar to Google Calendar:
The flow works successfully as below:
Google Calendar to Outlook Calendar:
The flow works successfully as below;
Please check if you have specified proper Calendar Id within your flows. In addition, please re-create your flows based on the following built-in templates and check if the issue is solved:
You could also take a try to create your flows from scratch based on the above two built-in templates. More details about creating a flow from scratch, please check the following article:
Thanks for the reply. I used different templates because I want a genuine sync, not just a copy of the events created. Support helped me out and things are working now. Except for two things - but maybe you can help me with them: