Final Cut Pro X & ProRes Major but Funny BUG

This must be the weirdest BUG I have ever experienced... And the most difficult to find. I found it via coincidence ;-)

I playback and use ProRes 4444 inside of FCPx. And generally there is NO problem doing so. Until yesterday...

In After Effects I converted a bunch of H.264 Canon 5DMKii movies, after denoising them, to ProRes4444.

I imported the movies into Final Cut X and immediately noticed that they were jerky in playback. So I loaded the original files and wanted to see whether they were jerky as well. They were not... Here comes the funny part...

The Original H.264 had AUDIO on them the ProRes version I had stripped the audio from as I did not need it. To better compare the two files (Don't know why I did it but I did) in the timeline I just copied the audio from H.264 file over underneath the ProRes4444-jerky file. Then I compared again. This time the ProRes was playing smooth as silk. I could NOT believe my eyes. I was cursing at the Mac but after smoking a cigarette and contemplating, I went back an deleted the audio from underneath the Prores 4444 file. Back to jerky. I put the audio back - jerkiness GONE...

So I did some more testing...

I took a completely different clip and imported that into After Effects.

I did the same denoising to it and exported TWO versions to PRORES 4444.

1 with Audio and 1 without it...

Then imported the two into FCPx...

We are talking TWO identical files here expect one has audio to it.

The one with audio played back silky while the one without was jerky.

I copied the audio (any audio will do) underneath the jerky one and it stopped jerking around.

I opened the two test files in QuickTime 7 and 10 and NONE of them were Jerky... This issue seems to pertain to FCPx only....

So if any of you export from AE to ProRes4444 and the guy on the FCPx station gets agitated because of the jerkiness,

before you blame adobe (like I did) tell him to just copy some sound underneath the sound-less video clip. That will take care of the problem,

untill Apple fixes the problem ;-)