curtismacc plate solving is performed at the begining to calculate deviations. After that internal sensor is used to measure your correction movements from that initial position. Measurements are relative from that initial point. So, if sensor is off a bit it doesn't affect the results.
The only really annoying issue is when sensor drifts and gives you wrong altitude value (absolute) at the beginning. Telling you are off turn it up to start the procedure. But right after plate solving tells no, you are too high move it down.
Anyway, it's a strange decision to use sensors for PA. Probably ZWO thought it would be easier and more convenient. But in reality it doesn't look so.
Usually it's pure astrometry task. Scope sees the stars and can measure movements. For instance Dwarflab don't use any sensors. Astrometry only. And it works flawlessly like a charm.
Also that Refresh button is some weird stuff. Never gives good results. So, in order to refine PA you have to exit the procedure and start it again.
