Basing this on 5 trachys, 2 scolys and a cynarina
Some seem to like feeding and some don't
You'll soon work out which you have, as the ones that don't just won't really be interested.
The bottom line is, it will only eat what it wants. You can't force it
My tank is heavily fed anyway, so there are a lot of available nutrients in tank without target feeding, which i think helps.