The bug
It looks like the search bar of the recipe book does not work if you just opened the recipe book and it was not open before.
Reproduction steps
Open your inventory
If your recipe book is already open, close it, close your inventory and reopen it
Open the recipe book
Click on the search field next to the search icon
✔ The underscore cursor appearsTry to type something
❌ It does not work
Linked issues
is duplicated by 7
relates to 1
Comments 5

I am able to consistently reproduce this and updated the report accordingly, I hope you are fine with that.
The issue only occurs when you created a new world and just created a crafting table, worlds that created from previous versions before 20w18a doesn't have this issue.

Can confirm on 1.16 pre2
All this time I thought it was a case of "the 2x2 grid doesn't allow searching, only the 3x3 one does".
Unable to reproduce.