iPhone 7 tells me I’m out of storage when I have 20 GB left...?

So I recently changed from a 64 GB iPhone 6s to a 32 GB iPhone 7 and transferred all my data across, which was about 20GB. It started redownloading my apps but then stopped downloading them and offloaded them? When I clicked on the icon to download them it would get a message saying I’m out of storage and a button to go to settings. When I click that button, it tells me I have almost 20 GB left.

iOS 11.2