I have mulitple data sources configured in my web service. They are all different endpoints, but the same logic. I use an OData connection to connect to SharePoint Online lists (our lists exceed the lookup column threshold for a sharepoint online list connector). In the past month, these data sources keep failing the scheduled refreshes, giving the error message that reads 'The credentials provided for the OData source are invalid' So I go into Data Source settings, choose 'Edit Credentials' and sure enough, the authentication method shows 'anonymous' instead of 'Oauth2'. SO I change it to Oauth2, sign in using my O365 creds, APply the changes. Then, just for giggles I click 'Edit Credentials' again and its already reverted back to Anonymous. This is obviously why these refreshes keep failing, but I don't know why it is not sticking to Oauth2.
I've tried republishing
I've tried replacing the existing file on the OneDrive and using the 'get data' to navigate and load the file from there.
I've triple checked the stored credentials in the source file
I've opened a ticket with Microsoft...no luck there
I double check on my datasource settings, it still works. I'd like to suggest you submit a support ticket for this issue and use "Fiddler" to trace the detail operation steps and send these records to them.