It could be your interface which seems not fully following the special modifications that an OBD serial INPA/GT1 interface should have on top of a standard serial OBDII interface.
This is a 100% compatible interface and the explanation + schematics over the BMW mods. Only short the Pin 7&8 from my vcds cable, and use it for bmw? It is possible to use an “old” vcds or vagcom kkl cabel and use it for newer bmw (2004-2011) with the software inpa? Here, you will get answers to questions below: