608 and 708 captions not embedding with exported MXF file.

All of a sudden my 608 and 708 captions are not embedding into my final exported MXF file. I've checked the settings, they are the same settings I've used for a couple of years with no problem. Went into Media and turned on "import captions with media" so that I can reimport final file into project to check to see if captions are there.  Still no success. This is the setting I always use.