Hi Roy,
Firstly, I'd like to collect the following information to narrow down this issue:
1. Do you change any settings in Office 365 OWA/ Outlook or iPhone recently?
2. Do other users in your organization have the same issue with you?
3. Who scheduled the two meetings? Is this person in your organization or out of your organization?
4. Is your Office 365 service upgrading?
Thanks,
Edward Qu