That is correct Google Voice operation: your calls go through your Gmail account by default.
If you are not logged in, which would allow you to answer the call on the screen, or if not answered by another phone, then the call is dropped to VM.
OBi is an add-on which simulates logging in to your Gmail account and allows you to connect a normal phone.
However it appears the first logged in application will grab your incoming calls.
Re-enable the OBi and verify under Status that it is connected. If you still do not get incoming calls, some previous app is interfering.