I made some ice cream that has been in my freezer for over 24 hours and is still soft. What gives?
Ok, has it frozen yet?
The first thing I'd say is that just because things in your freezer are frozen doesn't mean it's the right temp. everything will be frozen @ 25 degrees, but ideally your freezer is around zero. The only real way to check is with a thermometer, or you could just turn your freezer down a notch and see what happens. Also, a full freezer functions much better than an empty one.
Barring that, other issues could be a super high fat content in cream used, or rather a low water content. The idea behind ice cream is to suspend tiny ice crystals in fat globules, giving us great texture. That's why we keep it moving when we cool it down, preventing bigger ice crystals from forming.
If the dairy used in a recipe doesn't have enough water it will be essentially like freezing lard. It just won't set up the same