iTunes Producer, ISRC problem

[T8HFS]

I have iTunes Producer files someone else has made that I need to change. The files have audio and metadata already in however, I cannot put the ISRC's in. The required field is grey

 

[T8HFS]

I have iTunes Producer files someone else has made that I need to change. The files have audio and metadata already in however, I cannot put the ISRC's in. The required field is grey

If only we burnt all heystacks, we could find all the needles