Movie Render Queue Not Rendering Alpha Correctly

I’m having some weird issues with alpha when rendering my sequence out of the Movie Render Queue. I’m running UE 5.5 on a Mac Studio with macOS 15.2 installed.

When viewing the rendered PNG’s in Finder, they don’t appear to have a transparent background at all. When I pull the sequence into After Effects (currently running version 25.1.0), the only transparency I’m seeing is in the upper left corner of the image. It’s static however, and doesn’t seem to animate.

I have “Alpha Output” enabled in my project settings. And here’s the render settings I’m using in MRQ:

Exports:
.png Sequence

  • “Write Alpha” checked

Rendering:
Deferred Rendering

  • “Accumlator Includes Alpha” checked

Settings:
Anti-aliasing

  • “Override Anti Aliasing” checked
  • “Anti Aliasing Method” set to “None”

Console Variables

  • r.MotionBlurQuality = 4
  • r.DepthOfFieldQualtiy = 4
  • r.Tonemapper.Sharpen = 0 (if I leave this out, I get a weird white border around my objects, and still no alpha).

Game Overrides

  • Default settings

What am I doing wrong here? The level itself consists of only my 3D assets, a directional light, and an HDRIBackdrop with it’s geometry component’s “Visible” setting turned off. I tried deleting the HDRIBackdrop entirely, just in case it was causing the problem, but it didn’t help.

Any insight would be much appreciated!

I’m guessing this must just be a bug in 5.5. I tried reverting back to 5.4 and my alpha rendered correctly. Just going to have to stick to that version of the engine for now I guess.

Do you have a small repro you can send? And can you send me a png example?