Minecraft - Why am I not catching any Treasure Items?

I followed the instructions on the MC wiki, namely:

In order to catch items in the treasure category, the bobber must be in open water. This is technically defined as the 5×4×5 vicinity around the bobber (2 blocks away horizontally, 2 blocks above the water surface, and 2 blocks deep). Each horizontal layer in this area must consist only of air and lily pads or water source blocks, waterlogged blocks without collision (such as signs or coral), and bubble columns. These conditions are checked every tick to determine if the player is eligible to receive treasure from a fishing attempt. If the conditions are not met, only items in the fish and junk categories can be obtained from fishing.

This is my fishing setup:

As you can see, the two layers below the water surface are pure water, 2 layers above are pure air and the shores (or any other blocks) are more than 2 blocks away from the bobber. I’ve also tried removing the boat just in case, even though it was out of range of the supposed 5x4x5 area.

I haven’t been able to catch any treasure items after a long time trying (I’ve caught dozens of junk items). Is the info on the wiki wrong or am I understanding it incorrectly?