NM. The new thing in 7 is that by default coverage does not apply to logged out/PSA/TTI stations unless you explicitly enable it. It would be the difference between a brdg-appr ringing forever and going to voicemail.
I'd look at the PPM flow and SIP NOTIFYs from One-X to SM and CM and stuff. The NOTIFYs will get a 200OK, but look in there. It might have "subscription terminated"
So, if for whatever reason, CM isn't aware of a live subsscription from a SIP phone 1234 that has brdg-appr of 2345, then when 2345 is called, and isn't logged in, CM wouldn't think that the brdg-appr on 1234 should be told to ring either because it isn't there.
Same like if 1234 and 2345 were h323 and had brdg-appr of each other but both were logged out and the call had nowhere to ring.
What if you add a brdg-appr for that extension on a H323 phone too. Does the H323 ring? If yes, maybe you have a PPM problem.