Gubi,
I am beginning to believe there is something amiss with the basic logic in both the indi_synscan_telescope driver and the indi_skywatcher_AltAzMount with respect to position vs. crosshair reporting. Another long night of testing (and not imaging).
I started with KStars/Ekos with the tablet running synscan and interfacing KStars with indi_synscan_telescope. I aligned with the tablet only to Jupiter. KStars showed Jupiter with the crosshair. I then did a tiny move to a close-by star. It moved in that area, crosshair and all, but the plate solving failed. It failed via max retries (4) and oddly. The first solve showed it about 1 minute 50 seconds off target. The second, 33 seconds (so far, so good), then the next was 41 seconds and the final was 58 seconds. This odd behavior did not occur when I plate solved with skywatcher_AltAzMount.
Then, I tried to move to M15, and the scope moved in that general area, but the crosshair moved "out of the universe." I don't like the synscan_telescope driver, so I blamed it and restarted indiserver with skywatcher_AltAzMount. I restarted KStars/Ekos. The crosshair was in the same place. So, I brought up Carte du Ciel. Same thing. Crosshair out of the known universe. Exactly the same postion as was displayed by KStars. It may be that the screen positioning routine for the AltAz mount drivers is just a bit broken. The scope clearly did not leave earth during the tests.
Different test tonight. I am going to try SkySafari on my Android with the SynScan Pro app to control the scope. If that works happily, I'll add in PHD2 with an indiserver running the dreaded synscan_telescope driver. I have, in past tests, had reliable guiding at least with that driver and PHD2. This assumes, of course, that it doesn't fight with SkySafari. That will just leave be back at needing to accommodate plate solving data.
So finally, a question: Do you know if there is a manual way to modify where the scope believe's itself to be with actual data from a plate solve? I'm guessing that setting new RA/DEC coordinates in the indi control panel triggers a GOTO....which would be bad, since it is already there.