Hi,
Thank you for letting us know your problem on ROG Keystone shadow drive function.
1. Shadow drive is a dynamic VHD rather than a real extra partition disk. The situation you encountered is normal for a dynamic VHD. Even though the space of C drive can’t be released, but the space of shadow drive is still normally functioning, please don’t be worried about this.
2. Keystone is a switch of shadow drive to turn on the hidden storage area but never an extra hard drive space for users.
3. We know that it may still cause inconvenience to end users, so our team will add the function to release your C drive space by a more straight forward way, that is by restarting your PC.Users just need to restart their PC, and the C drive storage space information will be synchronized. This function will be released by later July 2020, please looking forward to it.
Thank you!