ursa broadcast g2 b4 mount 4.6 mini pro

hello. the seller from ebay sold me a camera with a mount from ursa 4.6. it is shorter as you can see. it is impossible to use objects b4 with it. it physically overlaps the matrix. can I somehow get a b4 bayonet from ursa broadcast? I don't know what to do.? It is impossible to use the camera