Problems with Linked Tables in Dataflow in custome...

I'm working in a customer tenant with my Pro license of my company. Therefore my user is added to the customer tenant as a guest user. The customer has a premium workspace.

I try to create a dataflow which should use a table out of another dataflow in this customer tenant. When I try to start creating the new flow with the option "Link tables from other dataflows", I see only the PowerBI workspaces of my company and not the ones of the customer tenant.
Is this not possible or is there any option to connect to tables in the customer tenant?