Powerpoint in Safari has stopped working (can only see first slide)

Sometime within the past 2 weeks, Powerpoint documents on Safari have stopped working. I am on the latest version of Big Sur with a 2019 MacBook Air.

Clicking a Microsoft OneDrive/Sharepoint link to a Powerpoint file opens in Safari, but I am only able to see the first slide. This occurs on multiple Powerpoint file links from multiple co-workers. I am no longer able to:

1) Advance to other slides

2) Download the file to the desktop Powerpoint app

3) Enter presentation mode

Using the same link in Chrome, Powerpoint functions fully. Safari had previously operated correctly until about 2 weeks ago.