I am using MacCaption with XDCAM!!!
I’m sorry, I don’t know how to fix it if your using a F75 Deck Personally I think those decks are obsolete already,
However, The U1 drive is a different story.
I had the same problem you had and as it turns out my problem was that in the U1 Utility software there is a check box labled “data item out” and it must be checked in order for Metadata to be recorded to the disk.
Hope this helps!!