Hi
I went through the same problem also.
It might be that your disk has become dynamic. Can you see data of your other partitions in GParted like unused space and used space?
Can you boot into Windows and check for your disk being dynamic or basic?
Another element to check is whether the Windows 10 install uses MBR or GPT partition setup. GParted (I think) gives you the option between MBR or GPT. Also when dual booting it is best to shrink C:\ drive using Windows Disk Management and use the freed space that provides to install Zorin to.
Could You run Zorin in Live Mode on the USB Stick? When You do that open Gparted and make a Screenshot of the Partition Overview and post it here. I think that could give us here a good Overview for Your Partitions.