I'm not rendering my clip with
any background. Ok, maybe I should layout my steps I've taken so far:
1. Was provided with a ProRes 422 (.mov container) clip containing the pre-animated 3D object over a solid chromakey green background.
2. Imported it into resolve, created a new timeline from clip, went to fusion and applied DeltaKeyer, which provided a very clean key with default settings (after setting the background color of course)
3. Exported the timeline as DNxHR 444 12-bit (one Premultiplied and one Straight Alpha)
4. Reimported the clips, put one on timeline above video clips, and tried to apply all kinds of blurs (built-in blue, Gaussian blur, Lens Blur) all of which produce this odd effect.
For reference, here's the original clip I used to key: