Most players do have a few mounts favoured, but the activation key for the summon indicates that if you have no mounts favoured, it will just draw from all your mounts.
However at the moment that doesn’t work. If I try it says I have no mounts favoured. Which is a bit confusing given what the activation actually says.
I’m not sure if its a bug for the key or a bug for the system but which ever it is, would be good if it could be fixed.
Along with the other issues currently making the mount system annoying.
Also, I note that despite setting the display of mounts to not include ground mounts, some ground mounts still appear. Examples include:
Ottuks of various colours, both scouting and war
Delugen
Riding Turtle
Savage Battle Turtles (of various colours)
Sea Turtle
The above are just for mounts I have, there are probably far more that I dont have.