Zorin OS does not detect Windows 10

[zabadabadoo]

I was going to suggest you look at this, but I see you have already found it.

No Dual Boot possible?

I have just stumbed upon this item which may be of interest to those that have a machine that has a SSD and a bigger HDD onboard. It refers to installing Ubuntu with Root on SSD and Home on HDD. Rufus is the chosen media tool. I guess ZorinOS can be substituted for Ubuntu and your preffered boot media creation tool can be substituted for Rufus. Do also have a look at the Comments at bottom of the article though.

I also suggest a look at @carmar 's post here, also the associated links he posted there.

Partitioning during installation

Once you choose "Something else" installation option, it will take you to the partition screen. Use “-” button on that screen to delete partitions and “+” button to create them. Delete the existing Windows partitions (unless installing alongside Windows) and then create root (/), swap, home (/home), and ESP/EFI (50 MB). ESP/EFI depends on if you have UEFI turned on in your BIOS, otherwise you don’t need it (the installer will tell you if you need it). If you have multiple drives, please make su…

There is an outside chance this thread may offer some clues:

I want to triple boot windows 10, Ubuntu and Zorin

I want to triple-boot Windows 10, Ubuntu, and Zorin. When I did ubuntu and windows 10 I saw both of the operating systems but when I installed Zorin I see only windows 10 and Zorin not ubuntu.

Also from the old Zorin Forum:
https://zoringroup.com/forum/4/15355/