Ok, I have a new but related issue. Whenever I power up my observatory, and launch EKOS, everything connects ok, but the dome will not slave until I first UNPARK the mount, then I have to let it track for a second before PARKing it again. Then one I UNPARK the mount, the dome will slave.
If I just UNPARK the mount after power on, it will not slave. I have to do the routine above.
Just for laughs I enabled both the Dome Simulator and the Nexdome driver and sure enough, the Simulator is doing the right thing - the Nexdome isn't... Super strange
quick update from last night's test and this may be a useful test for you too. Try the Dome Simulator and see if the same behaviour occurs.
In my case, I was running the Dome driver on a remote INDI server (so I don't have to run a USB cable from the RPi riding on the OTA down to the Nexdome rotator) - it turns out that the dome driver isn't getting updates from the mount driver, in my case.
We (@knro & myself) were able to prove out that the Simulator slaved locally but not when loaded over the network. You might be able to use a locally running simulator to see if it's the iOptron driver that's the source of the problem....