Allow external users to share reports

Hi!

I'm having problems with allowing an external user to share a report to other users at his company. I've set up a shared workspace where I Allow external guest users to edit and manage content in the organization, which works great. My guest is able to access the workspace and create reports based on the datasets in it. 

The problem is when he in turn tries to share the report with his collegues. When he does the recieves an "Permissions required" error, even though he is a workspace admin.

I've ensured that the "Guests can invite" setting is enabled in Azure AD External collaboration settings.

Is there some setting I'm missing, or how do I enable my guest to share the reports from the workspace with his collegues?