Avalaon MM BFM read problem

It works if I manually instantiate the BFM in the top-level file and not in the QSYS with the IP. This will prevent that QSYS inserts an interconnect between them which does more bad than good.

Anyways, I would like understand the problem because it would be more confortable to use the BFM in qsys.

There must be a wrong or missing information anywhere, which causes the interconnect to build something wrong between the BFM and the custom IP. Any suggestions? Is there a parameter which tells the pipeline bridge to work without readdatavalid?