I do have pretty hard to solve ( of course from my perspective

I created simple HDA with POP, timeshift to try why my particles couldn't draw a mask on my landscape ( but that's a different story ). Then I put it to the UE4 level and collision didn't work, particles were just falling without any collision at all. After that, I tried it out on a
simple level and guess what… it worked. But after trying it on another default level - VR one, it didn't.
I was checking, rather quickly world settings and those were looking the same ( but I could overlook something )
I attach every file that I could and thanks guys in advance for any help!