I can 100% confirm Chris' analysis. He helped me figure out the same problem earlier this year when I had the same erratic behavior with an iOptron SmartEQ mount, which - importantly - uses the same hand controller as the CEM25P.
The culprit is the DST setting.
Set that that to 'N', i.e. no, and your problems will go away.
By the way, I am now using the CEM25P as well and there is no problem with meridian flip, works like a charm, provided the time zone is set correctly.