Here's the sitch:
T calls a hold on B1. A1 should have had the 1+1, but a throw-in was awarded instead. A sets up the half-court offense, and after a rebound, knocks the ball OOB.
Let's say the error is discovered. The lane is filled.
Let's say the official signals in B's direction. What happens to the lane?
Let's say B4 now has the ball OOB for their throw-in.
I'm guessing that the definition of COP is that B has the ball, and does not include only that the official has ruled that B gets possession.