That is because the structure of the system partitions is different in Windows 10.
Please refer to the following options if you like to return to your original system:

1. If you have created the recovery media with “MSI BurnRecovery” before upgrading to Windows 10, you can use the recovery media to do the system restore. Find the MSI BurnRecovery guide here.
Video Tutorial:

2. Otherwise you could use Windows 10 recovery function by referring to the FAQ.