I am also still having this problem. I have a security group with all my users in it. I have granted access to that group to edit the Excel File AND the PowerApp itself. They still get the error when loading the app but, the app itself works as expected if they click the 'x' on the error.
I have tried revoking access and reinstating it too, unfortunately this didn't work for me.
I think it might be something to do with user rights? ie. I have a user with "no licenses" that I want to be able to view files in a Sharepoint site, or in my OneDrive - this was working for some time, but about 2 weeks ago it stopped working 😞
Given this thread is a little bit old, I wonder if this is a new problem, or a re-hash of this same problem in this thread coming up.
Some sort of weird thing going on.
I have this issue, users i shared the app with, get the message "Connection could not be added. try again" and this happens only with OneDrive for business all the other connections were done with no issues.
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