Adobe After Effects CC Doesn't recognize Alpha Key for imported DNxHD (.mov) clips

After Upgrading To Adobe CC, we faced a problem when we try to import our HD assets (Quicktime .mov Codec: DnxHD 1080i 120). they are imported as one layer.. there NO Alpha key.

These Clips dont have such problem when we import them into Adobe After Effects CS6.

Please Adobe, we need a fast solution. this is urgent.

Note that we tried to download the last version of AVIDCodecLE package with no result!

thanks for any idea.