I have a CEM25p that I use from time to time and since upgrading to Kstars 3.6.6 on latest Stellarmate, I am unable to guide.
The system is: CEM25p + Redcat51 + OAG with PlayerOne Ceres M. Focus is all good, I can see plenty of stars from the OAG.

This is what I get:
2023-09-05T22:25:50 Guide DEC: Scope cannot reach the start point after 70 iterations.
Possible mount or backlash problems...
2023-09-05T22:21:42 DEC drifting reverse...
2023-09-05T22:19:23 DEC drifting forward...
2023-09-05T22:19:02 DEC backlash...
2023-09-05T22:18:34 RA drifting reverse...
2023-09-05T22:17:39 RA drifting forward...
2023-09-05T22:17:39 Calibration started.
2023-09-05T22:17:39 Auto star selected.

I have reset all the guiding value to default, tried from 2.5s to 5s exposure, 1x1 & 2x2 binning.
A bit lost as to why it would not work, the imaging train is set to guide via mount.

Just found www.indilib.org/forum/ekos/13212-guiding...ration-failures.html which I need to try tomorrow and see if the issue is the same.