One of our developers noticed that setting showFlag.CollisionVisibility 1 in one of our production levels seemed to omit most collision geometry in a Development game build. I was more familiar with showFlag.CollisionPawn, but that flag has the same issue. Everything seems to work fine in PIE and when I tried a test level everything seemed fine at first, but then I noticed a select few assets were indeed missing in the collision view. Most of the test level is composed of simple block-out meshes which do not have Nanite enabled, but the pieces with no collision drawn (they do have collision) were production assets with Nanite enabled.
At this point I decided to do a simple test. I put a spherical mesh, Nanite is not enabled, with sphere collision into the level. Then I duplicated the mesh, enabled Nanite, and added an instance of that mesh to the same test level. Both have collision as expected and the geometry gets drawn for both when I look in PIE, but in a cooked build the Nanite-enabled mesh does now show up in the collision view.
It is my understanding that the showFlag.CollisionVisibility and showFlags.CollisionPawn views should work in Development builds of the game, but this doesn’t seem to be happening for StaticMesh assets that have Nanite enabled. Since nearly all of our production assets are going to have Nanite enabled this is going to make the collision views in game builds entirely unrepresentative.