Can Hostas grow successfully in full sun or do they need to be grown in partial sun to full shade?
I use to have some that had west sun from noon to sun down and they were very nice, now I am hoping to plant some in full sun.
Hostas in general like a fair bit of shade, so I am surprised you had success with some that had all afternoon sun - especially as the sun in the late afternoon in Australia does tend to be scorching, which will burn Host leaves.
Wisconsin is quite northerly, being up near the Canadian border so that might explain it.
My suggestion is to avoid full sun, though there are varieties of Hosta that can take more sun than others. If in doubt always check with your local nursery who will be aware of your local conditions and the capacity of the plants they stock to handle it.