I set up my 32-bit raspberry pi and downloaded and built the Hamlib 4.6~git. The F and f commands worked perfectly. So I don't think the problem is the 32-bit OS.
Here are some things to try. Make sure you do not have split Rx/Tx. The F command is really the Rx frequency. The I command is the Tx frequency. So test with the "I" and "i" commands and see what happens. Also, make sure you are not using multiple receivers.
I would still like to know if rig 2 works. You are using rig 10. Try rig 2.
Jim
N2ADR