There are issues with Hamlib 4.4 (possibly earlier versions, as well) that prevent rigsync from working correctly when built with it.
If you need Hamlib 4.x to support newer rigs, it is recommended that you use Hamlib 4.x's rigctld to establish a server, eg:
rigctld -m 1022 -r /dev/ttyF0 -s 38400 -t 4533
And rebuild rigsync using Hamlib 3.3 and connect to the server instead of to the rig's serial port.