Reading the notes, What’s Fixed in 2021.6: The following has been fixed:

Bug Number: MCCET-3702 is in the bugs fixed, I'll download it and give reports here if somebody is interested.

Ah, then I must have misread. Do keep us posted! J

Darson:

Reading the notes, What’s Fixed in 2021.6: The following has been fixed:

Bug Number: MCCET-3702 is in the bugs fixed, I'll download it and give reports here if somebody is interested.

That is not how I read the document.  I see Bug Number: MCCET-3702 in the Limitations section with the workaround noted earlier.

jef:

That is not how I read the document.  I see Bug Number: MCCET-3702 in the Limitations section with the workaround noted earlier.

Unfortunately you're right Jef. I misread.

So please Avid programmers take note, thanks.

Job ter Burg:

Darson:

Do you think this is the problem? UHD?

Someone recently told me that is an issue in MC. The problem is the interlacing happens before the scaling, which screws up the resolution. If possible, cut in P, keeping the additional resolution, mixdown in P, then create an I from that mixdown.

Just an update, it works, it doesn't matter if I edit in interlaced or preogressive, before exporting I switch in progressive mode the project and I make a video mixdown, I put it in an upper layer in timeline, then I switch back to Interlaced and export Prores or MXF, the moire from progressive clips in 4K, drone or camera, are much less flickering and retain a much higher quality. Yes, it's time consuming and a step more to do, but it works. Hope in a future version of MC it will be less tricky.

Thanks Job ter Burg for the hint.