When TAB is bound to open and close inventory you CAN open your inventory when pressing tab but you cant close it.
When pressing TAB when your inventory is open it does this. (shown in pictures)
The first picture i pressed TAB to open my inventory and the second screenshot i try to press TAB again to close it but it highlights the recipe book.

This has been an issue since a few snapshots back. have not tried it in all the snapshots but it has been a problem since atleast 19w14a, thats when i first had this problem.