Why is my home-made feta cheese bland?
Just one day?

Feta is assembled in one day but it is pickled in a brine for at least a week. Recipes I've used call for 10 days.

This time gives bacteria extra time to work and make the product more sour.

I've had good success just using buttermilk as my mesophilic starter. I suspect your starter will be better than mine.

Just give it time.