Water isn't acting like water

I'm making a generic content mod where I add whatever I think of. I'm on Mac and I'm using MCreator 2026.2, build 27711. The problem is that whenever I add a liquid and set it to water, none of the water behaviors apply. I can't swim in it, it doesn't interact with other liquids, and on survival I don't drown in it. It still spreads like water, and the water fog still applies while inside the block. This happens with every liquid created if its set to water.

How do I fix this, and once it's fixed, how do I make it form a specific block when it connects with any other liquid?