MS Graph API: OneDrive resource not found
<p>I'm building a Windows service that connects to OneDrive for Business via the Graph API using this method:
<a href="https://graph.microsoft.io/en-us/docs/authorization/app_only" rel="nofollow">https://graph.microsoft.io/en-us/docs/authorization/app_only</a></p>

<p>I've successfully authenticated my application and have a token for making calls to Graph API.  I have given my Azure AD application permissions to both Windows Azure Active Directory and Microsoft Graph (all application and delegated permissions have been selected for both).</p>

<p>My goal is to get the contents of a folder that resides in a specific user's OneDrive.  I need to make the following Graph API call:</p>

<pre><code>//graph.microsoft.com/v1.0/users('user-guid')/drive/items/long-item-id-here/children
</code></pre>

<p>I can execute this request successfully using Microsoft Graph Explorer (logged in with my Office 365 credentials).  When I try to make the same call as an application (using the auth token received above), I get an "itemNotFound" code with the message "The resource could not be found." (request-id: 
5e814dce-c4c2-4615-90e6-ea8ab90cbc49).  However, I am able to query the root and the "folder.childCount" property shows the correct number of children in the root:</p>

<pre><code>//graph.microsoft.com/v1.0/users('user-guid')/drive/root
</code></pre>

<p>I've set the folder's sharing to "All Authenticated Users" and I still receive "The resource could not be found" from the API call.</p>

<p>Any ideas on what I'm missing here?</p>