So far I've only noticed this after starting Fldigi in remote mode from CQRlog and then letting both run for several hours. The symptom is that the docked rigctl display in Fldigi will momentarily flash some odd value and then go back to the rig's actual frequency. Closing Fldigi resulted in CQRlog losing the actual rig frequency and displaying the garbage value. I'm guessing that when Fldigi flashes the garbage value coincides with when CQRlog polls for the frequency. I'm not sure Hamlib is suited to two C API apps polling a rig at the same time.
As I'm also the Hamlib maintainer for the FT-920, I'll play with the CAT timing values and see where this goes. This will seem to be a longgggg debugging session. :-)
The alternative will be rigctld I suppose.