Windows refuses to shrink volume beyond a certain limit, but I need to clone the data, what do I do?

Windows has the bad habit of placing essential Windows files at the end and the middle of the system disk. These files are unmovable, probably because Windows addresses them directly by sector-number, so become a problem when resizing down the disk.

you should first disable the page-file and swap space, then defragment the disk to move all sectors to its begining, and resize only using Disk Management. Return the above after the resize.

To reduce the Windows partition to the minimum:

• Turn off hibernation
• Disable the page-file
• Empty the Recycle Bin
• Defragment the disk with a third-party product the allows choosing a defragmentation mode that consolidates empty space at the end of the disk
• Resize the disk to a size that still leaves several giga of free space
• Clone the disk
• In the cloned system, undo the above manipulations.