ChanSpy B option doesn't work perfectly

Hi everyone!

I would like to use ChanSpy (with B option) to whisper into the both side of a bridged call, but unfortunately it doesn’t work perfectly if the bridged channel’s one side is an external/incomming call. Only the caller/incoming side hear the whisper.

As I see all relevant channels are attached to the ChanSpy whisper chan.

Any suggestion or idea?
Thanks!