Blue artifacts after adding color correction

Hello

I am using an older version of FCP 6.xxx
The issue I am having is that after color correcting footage from a nikon d600, these blue artifacts will show up if I reduce/increase the black levels using the color corrector. The files are prores HQ files that have been transcoded from the d600 footage. Is there a better way to transcode / format d600 footage for editing? The end results is that they need to be encoded into photo Jpeg files

Thanks
Sean