Extra collision boxes?

Platform: Windows
IDE: VS Code
LUA Level: Beginner

Hello all,
I am adding collision to tiles and props in a procedural generation using setCollideRect (objects extended from playdate.graphics.sprite). When I spawn just the tiles it's fine;

(sorry new users can only embed one image)

but when I spawn the props on flat sections of the tiles, I get these random collision boxes;


(outlined in red)

I have tried setting the collision response to freeze, or even overlap with little success. The Props are spawned -16 (size of sprite) above the tile, but as you can see at various places I get an extra collision box? Unless I am miss reading this.

Any ideas what would be causing this behaviour?

Regards,
Ian

Just an observation: the odd boxes look like they're being positioned by their centre rather than top left?

Problem is they shouldn't exist; I use the same method for adding the collider to the prop and tiles;

self:setCollideRect(0,0, 16, 16)

and as you can see, there are the correct number of boxes for each prop/tile, without the extra ones.

I think next step is to make a minimal reproduction of the bug.

The dragon looks great!