Script works with BoxCollider2D but not Tilemap Collider2D/Composite collider?

I’m sure it something obvious that I’m missing, but I’m going round in circles so here I am.

What I want to happen is, when the player enters the tilemap layered Water, and the water reaches the trigger collider on the players head, the player begins to take damage.
Currently the water tilemap has the following components:

Annoyingly, if I add a BoxCollider2D to the water, my script works just fine, but I don’t want to have to individually shape the collider for every body of water I have, I’d rather the collider work like it does for the ground with the composite. Anyone have any ideas?

Ah I figured it out, it was something related to the sprite. The sprite I was using was transparent, I used a non transparent version and it worked! I just made it transparent via the Tilemap component > Colour