This issue can be reproduced in 5.7.1, and it’s not a simple visual bug. I initially discovered that the problem was that Niagara leaf particles using GPU Distance Field collision were not colliding with a double-sided floor, but re-importing the same mesh without materials allowed for proper collision and they stayed on the surface (this took me a lot of time).
I removed double-sided textures from all materials, slightly changed the build resolution in LOD Build Settings to rebuild, and the holes and artifacts in the MDF disappeared in the viewport. The artifacts also appear to be related to the current camera (see this image). More details are similar to Distance fields issue
Due to confidentiality requirements, I cannot provide my screenshots.