Apple Pro Res 422 / FCP7 render issues

Hello,

I do a lot of timelapses and have pretty good workflow for all this. However, I am experiencing one issue that makes everything a bit difficult. I appreciate if anybody could help me.

My workflow is:
1. Shoot some stills RAW
2. Develop in Adobe Camera RAW
3. Import stills sequence and render in AfterEffects CS4 to AppleProRes 422
4. Import to FCP7 and edit
5. Grading / color correction
6. Publishing

All works fine, however I am having very often an unpredictable issues with the Apple Pro Res 422 codec under FCP7.

I always render a bunch of sequences from AE using the same settings for all files. The only difference is resolution.

My render settings for exporting from AE are:
- Apple Pro Res 422 wrapped in MOV
- render in 10-bit YUV from RAW 16 bit sequence files
- AE project in 16 bit
- Resolutions of rendered all files around 3500x2500 px, this vary from file to file.

The sequences render fine in AE.
The sequences play properly in QT, I can import them to FCP properly, play in FCP properly. I can drag to timeline, scale, rotate, scrub etc.

However: Some sequences fail to render in FCP7.
When I drag them to my working sequence in timeline (Usually a Full HD 1080p, Pro Res 422, YUV), scale down (usually) and try to render timeline footage (don't mean exporting here yet) I get the following error:
"Codec not found. You may be using a compression type without the corresponding hardware card."

This happens on many computers including iMac, MacbookPro and a Mac Pro.

I discovered that setting the footage size to even width and height figures when exporting from AE eliminates the problem sometimes, but it does not help in all cases.

Also it sometimes help if i take such sequence, crop and export using QT under the same settings, just a few pixels less in size. But again - it helps sometimes.

Can anybody help me with these?
Anybody experiencing similar issues?

Thanks a lot.