BW upgrade 7.31: RFC_NO_AUTHORITY dumps

Hi BW experts

After our upgrade to BW 7.31 users get error message while accessing via BEx to their data.

In backend ST22 dumps are generated.

The object S_RFC is given. When adjusting the role with additional function groups, it will dump again with another function group.

Are there any ideas how to fix this problem? Is it known?

Thanks