Hi @bsclau ，
Welcome to our forum, please kindly understand here we mainly focus on general issue on Outlook desktop client. According to your description, I understand you have issue with REQUEST METHOD on owa, which may be more related to icalendar. I have researched a lot about it and found a related thread, please kindly check if it could also be helpful to you, if you still need further assistance about it, it's suggetsed to post your issue in other icalendar related forum, thanks for your understanding and hope your issue would be resolved soon.
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