Hey, G11 and G8 owner, here.
Do you have a real time clock on the Pi4? With StellarMate on Pi3, once I made sure my RTC was configured, the issue with the G11 resolved.
I ran into the same problem with Astroberry on Pi4 and G8, but this time with RTC, found that once I switched cables with the G11, it was good, so my cables are faulty on the G8- waiting to replace them. Are you using the latest firmware update on the Gemini2? USB or LAN? I've always stuck with the USB-B. Are you using the newer Gemini2 (with only one 12V input)?
I also had issues with the G11 after RTC issue resolved them, but that was back when I was grabbing nightly builds whenever and it resolved after reverting to last stable build, if I even remember that situation correctly- this was also with StellarMate on Pi3.
I have issues with my Losmandy mounts often- I boil it down to half me and half mount/OTA. Really not sure why I stick with it, but I see others with such great success, leaves me confused often.
Best of luck, I'm curious to see how it turns out for you. I'm currently on a mission to get the PiZeroW powered by the Gemini USB-A port with dongle and connected to the USB-B input to run the mount over bluetooth with the Pi4- one less wire up to the OTA always sounds appealing. I've only made it as far as testing power from the Gemini to make sure it can handle it but looks good- I blab all of this because learning more about the general Gemini issues will be a positive experience for us all, I hope. Sorry for the semi-hijacking, please do let us know what you find.