OK, fair enough. Yes, it does seem strange.
All I can suggest is keep trying. Are you using WSJT-X, or JTDX? I recently switched over to JTDX, because it has better decode sensitivity, as well as some other features that I like. If you have both programs installed, perhaps you can try one or the other in F/H mode, and see if that makes a difference.
Also, it's possible that something is not configured correctly on the Fox end, but I wouldn't know exactly what. There are a lot of settings that the Fox can enable.