SENSITIVE DATA HAS BEEN REMOVED FROM THIS TICKET ACCORDING TO JFROG'S INTERNAL POLICY.
Performing a system import, while running as HA (even with one node) fails with the following error:
My tests were from version 5.6.2(HA) to 5.8.3(HA). (also to 5.6.2/5.7.0)
Once from RPM to Docker, and other from Docker to Docker.
As a workaround, you can start the target server as a standalone, and after running the import convert it into HA.