ok yes this is a common issue, it would be nice to have the coarse tuning working, but at
present the tuning will happily lock on a signal that's pi/4 offset from the desired
one (that's 1,200 Hz at a 4,800 baud rate). The C4FM demod is broad as a barn door
but doesn't work well with simulcast, which is what you're probably using there.
Suggest adding a "-q -1" or "-q 1" parameter to adjust the tuning -
what you want is to get rid of the "tuning error" messages. The Datascope and
C4FM tabs can also help show you whether the tuning is off, but for general reception you
should stick with the constellation display...
Max