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MakeMKV v1.16.5 win(x64-release) started
Opening files on harddrive at R:/Under Siege 2
Evaluation version, 29 day(s) out of 30 remaining
Loaded content hash table, will verify integrity of M2TS files.
Saved AACS dump file as C:\Users\william/.MakeMKV/MKB_v3_unkn0wn_3A46.tgz
The volume key is unknown for this disc - video can't be decrypted
Failed to open disc

MakeMKV v1.16.5 win(x64-release) started
Opening files on harddrive at R:/hard to kill
Evaluation version, 29 day(s) out of 30 remaining
Loaded content hash table, will verify integrity of M2TS files.
Saved AACS dump file as C:\Users\william/.MakeMKV/MKB_v28_Hard_To_Kill_AD8A.tgz
The volume key is unknown for this disc - video can't be decrypted
Failed to open disc

"Opening files on hard drive" means that MakeMKV does not have access to the information on the original optical disk to create the decryption keys. When you are doing that, you have to provide the key data separately.

If you have the original disks, you can have MakeMKV extract the decryption information from them.