The CI-V trace settles it: the IC-7851 answers 27 10 01 with FB and 27 14 00
with its mode, but refuses 27 11 in BOTH shapes — it controls its scope over
CI-V and never streams it. Its last firmware is from 2016, older than the
waveform stream itself; Hamlib's caps claim otherwise, the radio is the
authority.
Rejected both ways is a permanent answer, so it is remembered and reported:
the panadapter says the radio does not send its scope, which is the one thing a
black rectangle could not say.