Are you sure it's working? BW doesn't support Tor.
I guess I have an explanation, I use a rooted phone with Orbot installed in transparent proxying mode.
When entering my main-nodes .onion address into BW Orbot is most likely handling the address translation.
Switching into the BW network monitor doesn't show a .onion address but a normal IPv4 one.
Does that make sense now?
Dia