Hi JustinChanHCCSS,
Have a Good day.
Thank you for posting to Microsoft Community, we are glad to assist you.
First of all, we apologize for the trouble and inconvenience caused to your work!
Based on your description and according to the issues related to series calendar details overwritten.
I have checked from our side, and seems at this moment it isn't feasible to undo calendar changes.
As a workaround:
- Could you checking the occurrence of the invite on the assistant Sent Items as this may still retain the information you needed?
- You can also get in touch with one of the attendees of the said appointment and see if they still have the original Details.
We do apologize not able to meet your requirements. However, thank you for bringing this to our attention, your concern is very meaningful and reasonable.
So, we will surely raise your concerns to our Product Development Team and hopefully this can be included in the future updates
It is suggested to submit your valuable feedback directly to the Microsoft product development team by either go to Help from your dedicated App > submit Feedbackor by posting on Ideas · Community (microsoft.com).
This is required because as we are from the community team, we can only assist you in troubleshooting the query and providing you required information for the feature’s availability status.
Thank you for your time and understanding. For other questions, feel free to add your post to the Microsoft Community.
Best Regards,
Microsoft Community Moderator