> My wife has an N4 running 5.0.1 with no issues re calling, so if there is an issue for these users it's an isolated one and not a systemic problem with all N4s.

That's a bit of a leap to declare that the issue is an isolated one because your wife is not having the problem. As it turns out, my wife had that exact problem with her Nexus 4 on 5.0.1.

How widespread is the problem? Who knows. From my perspective it seems like the 5.0 release has been a bit more problematic than previous major Android upgrades.