Yeah I meant to say that in my post, I was in my custom skydome with atmospheric fog in an otherwise blank level,no planar reflection actor in the scene.
Do you want me to rename the thread to fit the description better?
Also I noticed that scrubbing a slider has a very similar effect on the object count & memory as this Issue:
while scrubbing (with “show framerate and memory” enabled in Editor Preferences → Misc) the object count in the top right corner rapidly increases in the exact same way, and stops when you release it.
Just wanted to mention it in case the two are related.
Thanks ! =)