Disappearing walls when I pass targeting reticle over them

Just curious if anyone has experience with this. I'm using room builder tiles and on exterior wall section when I'm in the Foundry 'play map' mode (doesn't matter if it's in edit mode or not) I'll pass my targeting reticle over the walls and if I'm facing them directly, they vanish until I move. Is that just a weirdo thing in working inside the foundry or am I going to have to find a fix to it to prevent it from showing up in the published form of the map?

I'm also having some issues with banners hanging from said walls not appearing unless you're looking at them the right way but I'm thinking that might be tagged to the walls doing weird stuff.