Ridiculous Tile set terrain... to learn

Godot Version

4.2.1

Question

So I’m still learning Godot and at the moment I’m trying to get my head around tile set terrains. I made a basic tile set to explore, with every variation of match corner and sides (discounting the middle square) I know this is a bit overkill but wanted to use it to play around with.

But it’s not working as expected - I’m assuming I’m missing something.

Here’s the terrain:

image

And here’s an example to show what I mean - the middle “cross” is with the terrain set and the right “cross” I’ve manually painted to show what I would expect to happern.

Why is painting the terrain set automatically choosing the tile with
000
010
000

instead of
000 101
010 010
001 101 etc?

Any insight appreciated - thanks