@T5-T6-Schnappi
Yes, VDash works perfectly through the adapter.
I don't really understand how that would work offline. I assumed the car has to be connected in order to access Diagnostics. In any case, I tried entering the VIN manually both with the car connected and with the cable disconnected, and it still doesn't work.
Yes, I'm using INT, which is the correct partner group for my car, at least according to the D5T5 lookup tool.
I just tried your procedure step by step: disabled VIN Decoder, entered the VIN manually, specified the car, clicked OK without using the "Read" button next to the Communication Tool. Unfortunately, Diagnostics tab is still grayed out.
My hardware isn't the greatest (Intel Celeron N2840 @ 2.58 GHz, 8 GB RAM, SSD), but I waited for about 30 minutes, so I doubt it's simply a matter of the diagnostic database taking time to load.
As for the adapter, I believe it's fine. Both HS-CAN and LS-CAN work perfectly in VDash, so the adapter itself and the drivers seem to be communicating with the car correctly.