Try NTFS.
I tried NTFS - the A600 didn't recognise it in either the menu or AmiBench.
Also tried ExFat, which worked in the menu, but again, didn't show in AmiBench.
Is the NTFS supposed to be a certain version? AFAIK different versions of Windows used different versions of NTFS, and I'm formatting it in Windows 10, which (I think) uses NTFS 5.1
EDIT: just thought of allocation size, does that need to be set to a specific size?
Just trying to think of everything I can