My initial Fantom ↔ MH test preset had a Ch Remap in it but I thought you’d moved on from that
Fantom-MH-KSP-Fantom is working
This looks like you’re not using Midihub between KSP → Fantom
A starting point like this…
…will enable you to MIDI Monitor traffic both ways.
As @Giedrius hints, using MIDI Monitor is the key to tracking (and reporting) puzzling outcomes.
If you’ve not used it much before, the tutorial might be useful.