Yes, we have our MEU on a switched AC circuit and are experiencing the same thing. We discovered over time that it was taking multiple boot cycles before it would finally work. It went undetected for a while because I start the system a long time before the musicians arrive. A couple of weeks ago it had continued to degrade to the point where it was up to 45 minutes before it would stabilize and work. I changed it to constant power to limp us through until we had a replacement sent. It has lasted one week and then failed the same way. We are working with the distributor to try and figure out what is happening. The AC mains was tested with nothing appearing out of the ordinary.
Did you ever get resolution?
Clint