It's possible that your panel doesn't support True Color, check your hardware ID in device manager, monitors, generic PnP monitor, Details, Hardware IDs.
And open the True Color package/ Export, and confirm whether your hardware ID is listed.
Did you see any error message when installing True Color?i have to modern 15 notebook and i cant install true color. https://tr.msi.com/Content-Creation/Modern-15/Overview
product introduction say true color technology is enable. Can somebody help?