Onions grew beautifully and bulbs are large, however, they have no flavor. What went wrong?

Moving to Fruit and Veggie forum.

What kind of flavor. Ther are many varieties of "yellow" onions ranging from sweet ones you can eat like an apple to so pungent that looking at them will make you cry. My first thought would be variety. Soil conditions also affect pungency but not to the level of variety.

So what's your soil type?
I'd almost bet you've got a nice pocket of loess.

In the state of Georgia, we have a few counties in the middle of the state where the onions are super sweet, And the wild persimmons taste like dried figs... The carrots... huge difference between the sand grown ones and those grown in clay...

Doesn't really sound like you did anything wrong...