Enchanting tables usually do a pretty good job at detecting when one or multiple of its bookshelves are blocked off by another block, but if on a 16 bookshelves enchanting setup you place blocks diagonally adjacent to the enchanting table and the bookshelves (as seen in the screenshots I provided), somehow, the game thinks this is invalid.

From what I know, bookshelves should only be blocked off if a block is between them and the enchanting table, this would make sense if the bookshelves were 1 block higher or if the blocks were 1 block lower but not here.

If this is intentional behavior, may I suggest changing this? Even for Minecraft logic, this hardly makes sense. And it's a bit annoying as well.