Teams Android Devices Endpoint Manager Corporate Identifiers

Hello!
I get various Teams Devices (Panels, Phones, MTRoA) enrolling to EndpointManager/Intune without any problem. Works perfectly. The enroll, they are checked against policies, etc.. all good.
HOWEVER, I totally fail with them showing up on the corporate iIdentifiers page.
I tried adding them with both a) their serial number as reported in the TAC or the device properties as well as b) their MAC address as suggested by some blogs. No difference.
They do not report on the corporate identifiers page ("never contacted  )and therefore do not move automatically from being personal devices to corporate owned devices.
Is there any trick I miss?
Thanks for any pointers.