Weird Interior Shadow Flicker

It is Lumen. First example doesn’t count, as it’s ‘in editor’, so you’re running a simplified setup there.

You can get rid of the red errors with the console command

r.Streaming.PoolSize 0

and by setting your lights to moveable.

As for the Lumen, that’s about as good as it gets in realtime, I think.

There are plenty of ways to tune it, though