Hi,
why should the system block anything here? Nothing is incorrect.
In MIGO you enter a plant and a storage location, never a warehouse number. If the plant / storage location combination is connected to a warehouse number, the system finds this connection and follow up functions are working (like a transfer requirement). But you do not have to have a warehouse number connected to this combination, you can also work with stock on IM level only, then you don't see a warehouse.
What plant and storage location do you see in the MB51? Or better, check the stock in MMBE. Is this plant / storage location connected to any warehouse?
And then you transfer the stock to your desired plant and storage location.
Brgds
Juergen