Particle emitter hits non-existent object

My waterfall drops particle emitter hits something before it reaches the water surface. I’ve checked several times if there’s some hidden object probably, or collision, but I couldn’t find anything. I moved the emitter to a different place, and it works as it should - particles bounce off surfaces and don’t get stuck in the air.

What could possibly cause this?

Ok, so. I’ve tried to delete walls, floor, ceiling, rocks… see if anything could be interfering. I tried to move the entire level into a different spot. And lots of other things.

But after couple restarts of the editor, it somehow fixed itself. I guess it was just a bug then?