Worldguard - Disabling water flow

I am trying to disable waterflow + lavaflow for my server's spawn so that people cannot grief the spawn. When I place water outside of my spawn's border, depending on the location, it flows in. It is really confusing as in some spots it does flow in and in others it just doesn't.

In the images the red line is inside the region. As you can see, in one of the images the water from outside flows in and in the other it doesn't. In both images the water is placed in the global region.

I have set the water-flow flag to Deny in both of my regions (SMP_SPAWN and __global__) Any help is appreciated, if you need more information LMK!