OneDrive files not returned from one tenant while other works fine

Question

Hi everyone,

We are developing an application that uses Graph API to access files on OneDrive. The application uses Azure AD Application to authenticate and authorize the access. The authorization flow works, and for one tenant, the files handling also works fine: after the application is authorized on the tenant, the files can be read and modified without problems. However, for other tenant, Graph API returns only one drive item without any child items, even though there are several drives in the tenant with files.

I am pretty much exhausted all my ideas here. The issue is not the permissions defined for the Azure AD application since everything works fine on the other tenant. The application authorization is done successfully, since Graph API calls return success code. It almost feels like we are connecting to a wrong tenant, but the tenant ID seems to be correct.

The communication with Graph API is done via Graph API SDK for .NET.

Any ideas on the cause for this? Any help is greatly appreciated, as well as any questions that may help someone to narrow the problem down.

BR,
Antti