I have not run into it previously but a 401 is an authentication error so I would check the usual suspects related to that. Because it’s working for some and not others my first shot in the dark is to make sure they aren’t logged into multiple google accounts in that browser. Easiest way to confirm is to have one try from an incognito window and see if same error there, or have them just go to like gmail.com in the browser and see which account they are in as. 

I figured out the problem but was too busy to post an update. It turned out a subset of users had their Chrome browser blocking ALL third-party cookies. Everyone else was only blocking them in incognito, which is actually what led me to the cause.

I provided instructions to manually allow the two blocked cookies, which added the google.com and docs.google.com domains to the allow list. 

I am getting the 401 error code but only when trying to access content through the app.  I have tried looking in settings but cannot figure out a fix.  Any suggestions would be appreciated. 

We got it to work!  Thank you 

Thanks to this post I was able to resolve for my user too! We had tried all the typical troubleshooting but they had an extra privacy extension in google that was blocking it. They made a few updates and it was fixed!

Thanks everyone!