yes, I heard all Falconer skill can’t be use while mounting…
we don’t understand why they decide it to be like that.
this image can explain better
so why? 
do whistling in real life need you to be on the ground to make a sound? can not you point a finger on your enemy (ordering a falcon animation) while mounting? can’t you not throw a doll while mounting?
on the other hand… is there any synergy with SR Falconer that will be so OP when my suggestion be implemented?