DNxHD input with TC overlay gives strange results

I'm trying to convert an DnxHD render in Compressor to different outputs, all with an overlay with timecode, as used in de video filtering.

The result:

To proress422HQ: The renders fades to almost completely black within 12 frames, and stays that way. And the timecode numbers are stacked over the previous frame TC number.

To Mpeg1: Also fades to almost completely black within 12 frames. Timecode appears properly

To Mpeg2: Starts at almost completely black, corresponding to the 12th frame in the other outputs. Timecode appears properly.

Thinks I have played with is the setting timecode to zero, and adjusting the alpha/transparancy. Even with transparancy to zero, I get the strange fading results.

When I insert a proress, thinks are oke.

So there is a problem with DNxHD and TC overlays. Anyone who had this problem before ?

Since we finish on Win7 machines, we can't work around the DnxHD format.

Thanks!