One question right back at you: Are you rewarding the vanilla animals or the modded ones? Make sure you use the correct path when adding the animal :)

I use Classic Flyers, and I have the same. Speed becomes level-able after reloading the server. Might have to do with CF replacing the flyers with modded ones, but it also happens to CF-flyers (double checked which were in the pack).

When adding the dino to the package make sure you are looking the modded tab and not the flyer tab during the pack creation.