I have powerapp application based on a SharePoint list. when I'm trying to open the app from my manager user, the list display with no problems. but, I when opened a regular user and try to open the app, it worked, but can't display the list from SharePoint, and gets the error in my message title.
Sorry to hijack, but I'm having the same problem. I have an app connecting to a secure list. (The list is only accessible by 3 users in the company.) I'm able to access and test the app successfully in designer, but receive the error on the phone.
It seems obvious that it's not passing the login credentials, but everything else I have on the app (less secure) is ID-specific and accessible.
Is there another step to ensure the credentials are passed to the secure connection?