When turning Steady Flight on if you have any ground mounts set as favorite then Random Favorite Mount will only use ground mounts. It will not use flying mounts at all. Skyriding is fine with favorite mounts.
I’m having the same issue as well, this is more or less similar problem as noted in Summon Random Favorite Mount does not work properly anymore - #73 by Stabier-daggerspine
I am also seeing this issue 8/30/2024 while in the Emerald dream area. I am able to use my flight form, but will not get any flying mounts from my summon random mounts spell/ability.
This has been an issue for over a week for me as well. Could we at least get some acknowledgement regarding this problem with an advertised expansion “feature”?