No add field option in iTunes 12.2.25
I'm trying to add fields to some Ballet and Dance videos I have imported into iTunes, as I have multiple artists/cast performing and doing the choreography for certain ballets and would be nice to differentiate them. My problem is the add field button, which used to be in the bottom left of the window has disappeared. I've searched on the communities and the apple website but they all say to expand the widow out and it should be there (but it isn't). Some older files that had been imported in a previous version of iTunes has Artist displayed, so I must have been able to do it at some point. It doesn't matter if the file is video or music either. I'm using a Macbook Air 2015 model. running the latest versions of Yosemite and iTunes 12.2.25.
If it's not possible etc thats fine I can live without it, as I can use the comments box and the description tab for these details, but would be useful to see them at a glance, any help would be welcome.
Many thanks
Simon
MacBook Air, OS X Yosemite (10.10.5)