Enabling viewport freezes engine

Yes, it is exactly as you described it. I figured it would be less demanding on my system to load the level without the viewport open/enabled. I have pinpointed the problem now anyhow. The name of my level that has the issue is “Level01”, I will use this name often to avoid confusion.

How i pinpointed the problem

  1. I migrated the content from my 4.11 FPS_BP project into a new/clean 4.12 FPS_BP project.
  2. I launched the newly created 4.12 project and loaded “Level01”.
  3. I could load “Level01” and fly around in the editor without problems, but as soon as I entered a specific post process volume the editor froze.
  4. I singled out the Ambient Cubemap in the post process volume to be the option that caused the freezes.
  5. I disabled the Ambient Cubemap in the 4.11 project and then opened a new copy of it with the 4.12 engine; “Level01” was loaded successfully without any freeze.

Now to the newly introduced issue

I can’t use the Ambient Cubemap in a post process volume in “Level01” without a freeze.

  1. I created post process volumes in other levels with the Ambient Cubemap ON for testing, but with no errors upon entering the volumes.
  2. I also created a new post process volume with only Ambient Cubemap enabled in “Level01”, but I still get these freezes upon entering the post processing volume in “Level01”.

I’ve only used the cubemaps/textures that comes along with the engine. The editor gives me freezes no matter which texture I use or which value the intensity got.I have no idea what it could be related to or why it would happen in the first place.