HI Enid,
Thanks for sharing that information with us.
I'd like to share a workaround that helped a customer in a similar situation:
We could make sure VBA is enabled in the Office 2021/365 installation.
Open PowerPoint, go to FILE > Options
https://share.getcloudapp.com/qGuqBvDq
Then you can go to Trust Center > Trust Center Settings > Macro Settings > ensure Trust Access to the VBA project object model is checked > hit OK
You then may need to close & reopen PowerPoint. And then try importing again.
If this doesn't seem to be working, I'd love to have our team take a closer look within a support case.
I hope this helps!