In the Hyper-V Manager, the virtual machine does not have checkpoints, but in the folder where the computer is stored, the virtual disk has several checkpoint segments with the avhd extension or avhdx.
Solution: Merge virtual disks of differentiation
Using the Hyper-V console, you will have to merge all the control points to the parent disk.
Before performing this operation, it is strongly recommended to make a backup.
Disk merging must be done virtual machine off.
Repeat the process until the fusion of all differencing disks and so as to have a VHD file or VHDX.
Once the VHD (X) is recovered, modify the virtual machine by attaching the disk instead of the differential disk.