Why does DLC 4 cause the matchmaking server to return no game?

It is nothing to do with any settings on my side, because if I disable the  DLC then games are returned. Re-enable DLC and no games are found.

Please provide us with a cause and solution to this problem. We have paid for these multilayer maps and cannot use them.

At the very least provide a timescale for when you expect a fix, or when you will provide an update on the status.

You have a loyal fan base that is getting frustrated by the lack of acknowledgement of a problem, and the poor communication regarding this problem.