Q. Raylight creates the links, but the video is all white or all black, or random noise.
A. Delete the link and rescan the MXF files. Make sure each folder in the path to your MXF files has a folder name less than 32 characters. Make sure the drive is formatted Mac OS Extended if you use long file names such as file names with the MetaData "User Clip Name". Make sure you have the DVCPROHD components installed by FCP 5 or 6. They are in the Library/Quicktime folder on your system drive, six files that start with "DVCPROHD" and end with ".component". If the slate frame is visible but no other frames are, most likely the original MXF files have moved or the path to the MXF files have a bad character or uses a folder name greater than 32 characters. If your source files are stored on an external volume, try renaming the volume to a shorter name with no spaces or special characters.
Q: Links render OK in FCP but in real-time playback show up as black
A. Make sure the sequence settings for frame rate match the clip frame rate.
If you have clips with pulldown, remove the pulldown in Raylight when you scan them by using the pulldown removal option.
If you are importing clips of a different frame rate that have no pulldown (e.g. 60P clips into a 24P sequence), instead import the clips into a 60P project, then export a 24P quicktime in ProRes or similar format, then import the exported clip into your 24P sequence.