I've just chanced upon this thread and can report that I am having similar experience with erratic behaviour during target centering at Sequence start.
I am using an Avalon M-Zero mount, StarGO, SGP v188.8.131.52, Astrometry.net.
I have SGP set to perform a SYNC after a successful plate-solve.
I attach a file with extracts of an SGP logfile that contains three unsuccessful atempts on centering on M33. I have annotated the log extract with what I think is happening. Basically I believe that when calculating the corrective action following a successful plate-solve, that the move is calculated using the frame centre location PRIOR to the most recent SYNC. Thus for example there is sometimes a significant error in the mount positioning and accordingly the mount slews such that at the next plate-solve it is quite close to the desired location. Now instead of a small corrective move the mount now makes a further signifiacant move to a position way past the desired position. The level of the error is such that I think the second move is being calculated using the original start position rather than the up-to-date coordinates determined by the plate-solve. I have annotated the log-file to show what I think will be the osition at the next-plate solve based on use of the earlier location and I find this is generally quite close to the actual position at the next plate solve.
My initial thought has been that StarGo has been slow updating its positioning following the SYNC command but do not know if this is correct.
I wonder if instead of SYNC I should use one of the other options SYNC Behaviour options on the mount TAB but not sure what impact this would have.
Having issued a SYNC command is there anything that can be done in SGP to delay the next centering request to allow the most recent SYNC information to propagate successfully fully to StarGo (if indeed StarGo is the issue).
Thoughts and suggestions welcome
a) My edited down and commented version of SGP logfile
b The full SGP logfile in two parts
commented extract from sg_logfile_20171006004857.txt (11.0 KB)
sg_logfile_20171006004857 Part 1.txt (523.3 KB)
sg_logfile_20171006004857 Part 2.txt (659.1 KB)