Compressor rendering issue with FCP 12 Noise Reduction

I just tried the built-in video Noise Reduction effect on the default settings and also on the maximum settings. I exported to Compressor and picked a ProRes 422 preset, then tried a 4k 8-bit HEVC preset, and they both exported OK and the different NR effect levels were applied.

This was FCP 12.0, Compressor 5.0, M1 Ultra Mac Studio, macOS Tahoe 26.3

Are you on the regular FCP 12.0 version or the Creator Studio version? Can you duplicate your timeline in FCP, delete about 75% of it, and try again?

Another useful troubleshooting step is to reset FCP preferences by launching the app while holding down OPT+CMD.

I tested it, also, no issues. Can you give more detail? What actually happens? Doe Compressor crash? Does it lock up? Does it give an error message? Details help a great deal.