GPT is the correct approach; no changes needed if it's GPT. A bit of note: switching from MBR to GPT is straightforward, but reversing it is more complex. If Windows is already installed on the volume, moving between formats becomes nearly impossible—typically requiring a full reinstall. For GPT volumes, you should turn off the Compatibility Support Module or ensure the BIOS is set to use only GPT volumes. On MSI boards, the CSM setting is labeled as Windows 10 Boot Mode and must be enabled, not disabled.
Ensure the system runs as a GPT-enabled device. Navigate to Settings > Boot and verify Windows 10 Boot Mode is active, enabling it or selecting UEFI. This forces the board to disregard older boot methods and only consider UEFI-compatible options. It’s still possible the SSD has a faulty connection or is malfunctioning.