@
jecilop - I think you're right, columns built from other columns (logical, composite, virtual, derived....) are not appearing in the columns to copy list - viz,
That library is my test library it was created on 2014-09-02 - there are no errors reported by Check Library.
I can't be certain I personally ever used this for a library with composite columns in the past.
What I can say though, is that the
calibredb -- clone command will copy all the custom columns including the composite columns. I was able to copy my test library to a clone with no problems - at a glance everything looks OK.
BR