There's an option for that. Labels are stored in NTFS metadata by default in new configs, but I'm not sure off the top of my head if it was always on by default in the past.
Also, if the drives aren't NTFS (or something blocks creating NTFS ADS entries) then Opus will fall back on the other method.
The setting is here in Opus 12 (near the bottom of the window):
And here in Opus 13 (which can also warn if a label can't be stored in metadata):
