Black halo on output using Compressor 4.1.3 and FCPX

Hi we have shot a fitness video in studio against a black background. When I output to anything other than the Master file in FCPX I get a thick black halo /line around the subject. I have tried various settings for output but get the same result. Can anyone advise how I might get rid of the halo?

If we can solve this issue the final sequence will be 11 minutes and available to download from the client's website as well as three samples being made available on Youtube. We aren't dealing with that aspect but need to be able to provide the finished sequences (11 in total) in a format that can then be adapted and compressed further to meet various outputs by the web developers.

Any guidance much appreciated.