It sounds like your fruit may not have enough juice. If you’re using canned peaches, there’s probably not enough juice with them. I’m really not sure. Usually I bake a cobbler in a 8x8x2 glass pyrex dish. If the fruit is not really juicy, I’ll use 3/4 cup flour, about 1/2 cup sugar, and 3/4 cup milk. (I always mix the flour and sugar together before adding the milk.) And I really use lots of fruit - sometimes twice what the recipe calls for.
I find that fresh fruit makes much better cobblers. I sometimes mix juicier fruits with less juicy ones….......such as peaches and blueberries or blackberries and apples. I rarely make plain apple cobblers but when I do, I always add apple juice. I don’t know what would be good to add to peaches tho’.
Hopefully someone else has some more suggestions! Good luck!!