ProRes 4444 pre-conformed sequence for colorist is compressing pixel depth in Premiere 24

@n_cushing1242 That's strange. Are you on an Apple silicon Mac that has the ProRes hardware encoding? If so I'd be very curious if you could try turning off that hardware encoding, restarting Premiere Pro, and then trying again. The hardware encoding is done by Apple and so it should be completely valid, I'm just curious if you see a marked difference.

The preference is found in Preferences > Media > Enable ProRes hardware accelerated encoding

Make sure to restart Premiere Pro if you toggle it.

Yes, I should have iterated that Render at Maximum Depth, 16-bpc, and Render at Maximum Quality were all checked on. As well as the Sequence Settings preview Max Depth & Max Quality, and our colorist said it was still happening.

This is the first time this kind of thing has happened and the editor had recently updated to 24. We don't send pre-conformed sequences to colorists often and do traditional preps with EDLs and source media. 

Will keep an eye on it and test it out with another colorist and report back next week.

As Neil suggested, please make sure your export settings include turning on "Render at Maximum Bit Depth" and also set the encoding depth from 8-bpc to 16-bpc, both highlighted green in my screenshot.

Curious. Did you have Max Bit Depth set both in the sequence Preview settings and in the Export settings? And did you have 16bpc checked in the export?

The main difference I know of between the 4444 and 444 is the addition of an alpha channel ... that fourth 4 ... but @Warren Heaton10841144 would know better I think.