just type in the mount name for the mount you want to use in the settings, uncheck "Use Random Mount" and "Find Mount Automaticly"
I'm having the same problem. I'm not picky about wanting a certain mount, but it is very obvious that something is up while im botting. I always use my Azure Cloud Serpent, and when botting it wants to use anything but that. (Yes I typed in the name, as well as the wowhead number, and yes i have checked and unchecked "Random" and "Automatic". Thanks for any update you can give us.