I can't explain it exactly how or why but having Fullscreen to NO aka fake window mode in Optifine prevents the search bar for being use-able or click-able.

So far I have noticed I either have to have
Fullscreen: YES
Resolution: Default

OR
Fullscreen: NO
Resolution ( here I put my native screen resolution)

and it MIGHT work but only about 50% of the time

I have to go back and forth and restart the game a couple of times if I want the feature usable.

Reproduce-able : always

I don't fix bugs caused by optifine, because it's a terrible mod.