There is a known issue on MPH with ccminer (see official MPH thread).
The owner of MPH has admitted it, and said the problem comes from ccminer, but the miner is working fine on other pools, so don't expect them to solve the problem.
People mining with SGminer don't have this problem.
I started XZC with MPH today as sprnova is down for wallet sync. If there is such a problem then I will switch. Thanks for the info.