[Chris Wright]

oops, I meant to say purge disk cache
any LUT’s applied?
it sounds like a combination of transitions or effects that causes the issue.
you could narrow it down by adding them back one by one until the error appears again.

[Chris Wright]

purging memory ever fix this?

[Chris Wright]

that’s one dilly of a problem! have you tried rendering from AE directly?
AE also has an effect called color profile converter. have you tried adding an adjustment layer and placing that effect over the top. input rec. 709 , output-16-235. it would lighten AE and then media encoder might re-adjust back.

[Chris Wright]

try plugging into another computer. audition can remove a lot of white noise with adaptive noise removal.

[Chris Wright]

uh, the free version is limited to UHD size.

[Chris Wright]

premiere’s render engine has two render output settings.
1. rec. 709
2. J2K only HDR ST2084 rec. 2020/P3 PQ/h.264 HDR
https://mixinglight.com/portfolio/hdr-essentials-getting-setup-in-premiere-pro/

All your RAW media(which are non-HDR) will not only be blended inside a limited colorspace, but the Rec. 709 will get also get burned in via rendering(except PQ J2K) and you will clip your P3 colors you spent all that time on grading.

The really hard question to answer is if color clipping occurs in the color engine itself. The answer to this is complex because technically, premiere can handle importing PSD’s in Adobe RGB(which is wide gamut) and can handle HDR Rec. 2020 h.264 metadata’d stuff. The real issue is how premiere is interpreting the media.

For example: if you import h.264 HDR with wrong metadata flag, premiere will hard clip everything and blow out your sky. It isn’t going to recover that information if you try to render out HDR again. It’s gone for good. So, it seems, the engine CAN handle higher color management, it just won’t give you the choice to. It’s in essence, hard coded in for special exceptions.

After Effects doesn’t have this problem because Adobe recommends setting the project working space to the LARGEST gamut that you have inside your project. This protects against clipping out of value colors from say, Pro-Photo if your output is also Pro-photo because a Working Space of sRGB would clip Pro-photo inside the color engine before it even got to the render engine.

If we had the equavalent in premiere, then the LUT/color profile transform would work. Unfortutately, a fake, low quality conversion won’t really get you anywhere. Information is lost forever. You can go down in quality, not up.
https://www.red.com/learn/red-101/cinema-color-management

(A very special separate color engine)
“Exporting J2K MXF files in PQ space

Premiere Pro’s J2K exporter now includes a 12-bit PQ option. When you select the RGB 4:4:4 12-Bit PQ option from the Chroma and Depth pop-up menu, a new drop-down list allows you to select the Color Space: Rec709, Rec2020, or DCI P3.”
https://helpx.adobe.com/premiere-pro/using/whats-new-November-2015.html

some more nasty color bugs:

bug#1: Lumetri’s saturation distorts colors into yellow
https://www.learningvideo.com/premiere-pro-cc-saturation/

bug#2: prores 444 render banding
https://forums.adobe.com/message/9202682#9202682

[Chris Wright]

you are correct again. mercury transmit sends data in rec. 709, as does dynamic link. premiere’s color engine can work in float via max bit depth but the color palette is limited to low quality rec. 709 unless you import metadated jpeg200, exr, or h.264 hdr footage. even cinema dng places an un-revocable rec. 709 burned in color.

[Chris Wright]

running too fast could be an indication that your media is variable framerate. mediainfo will tell you that. use handbrake to convert to constant framerate.

[Chris Wright]

you’re right about everything. the only thing I see worrysome is that grading in a fake P3 transform won’t give you any extra color over rec. 709 if that is premiere’s maximum color palette. it is not a professional coloring tool. davinci will color manage all the way through like after effects does.

[Chris Wright]

its an overlapping UI bug. as to when it will get fixed, only adobe knows. you can update the bug form so that it gets pushed to the top of the to-do list.

https://www.adobe.com/products/wishform.html