hello, not sure if i am just using it wrong, but I have added rules to try and make it so that I only have ground mounts on, but it keeps choosing flying mounts

I'm not sure what you have done specifically but the default on Siren Isle is to use a ground mount, since you can't fly there yet. If anything else is happening it must be a specific rule you have set up.

One thing to note is that if you choose the "Random Mount" action in your rules it will not choose the best type of mount for the area. If you want the smart behaviour you need to use "Smart Priority Mount"