Thanks Anina!
I’ve currently got a workaround of sorts. I set a daily recording from 19:00 to 19:01 which turns the box on at least once each day.. As long as I set any record requests before 7pm (for programmes which start after 7pm) then it works.
I don’t think you will find.a way to allow the Horizon box to accept record requests when in Eco mode, so my workaround might be permanent! 😉