I just posted this same solution in another post, but it may help here as well....

Sometimes with line-related problem that I have trouble sleuthing, I'll just make the line a private line to an exention to erase all other programming from the line,let the system update, then re-program it as needed.

This may do the trick, if not, you're no worse off.

Punch down all your damn pairs!..........(please).