Which output? Is it output 7 & 8? Some earlier batch of MD888+ may have this problem due but I learnt that this problem has been eliminated in the later batches.
The best way of wiring up a control panel is to apply power in two stages using a multi-step rotary switch which will supply power first to the PLC and then to the load. When powering down the power to the load is first disconnected, then the PLC. That will prevent any undesirable glitches during startup.