In this case
https://support.simulationcurriculum...6-pro-in-MacOS the Skysafari support guy immediately suspects the cable / driver and recommends a Keyspan cable.
If that doesn't sound like your problem you could open a separate thread on their support forum?
I run 10.12.6 , have an old Prolific adapter, an iOptron mount and instead of SkySafari, I used
Kstars as planetarium app.
Completely different to your setup
I mention it because if you can't get hold of a Keyspan-adapter quickly, you could at least test your setup using kstars. Kstars isn't quite as fancy as Skysafari, though. Just meant as a testing suggestion to figure out if it's a SkySafari-specific issue or an issue with your adapter or cable connections.