Also, what remote are you using and what firmware version runs on the Crossfire transmitter and receiver.
When I first developed the driver for it, I used the RE1 for this, so if you also have one, there isn't really any reason for incompatibility.
Actually, it seems like there's actual data coming in (the flight mode switch toggling back and forth). CRSF packets have a CRC, and if that checksum check fails, the faulty packet gets rejected. So it seems like data makes it through and it gets messed up somewhere downstream the radio link.
Wherever CRSF is involved, said packets are CRC'd, and if they're faulty, should be rejected at whatever boundary they're being passed on (CRSF transmitter -> CRSF receiver -> Flight controller, and in case you're using a FrSky remote with OpenTX, also Remote -> CRSF transmitter). Our Crossfire driver definitely rejects faulty packets. So in principle I'd like put the blame on the remote or something in-between.
On the other hand, there seems to be repackaging happening somewhere, because I've identified a bug a few months back where correct telemetry was sent to the CRSF receiver and it arrived faulty at the remote. If you're on an older firmware, it'd probably be an idea to upgrade. Last version I've installed a few weeks ago was 2.25.