Charlie's most recent post may be a key here, and also AudioTrack's question about track colours.
The MIDI shown for RealTracks is
not the source of the sound, they're a transcription of what's played by the RealTrack, which is audio. If the tracks as seen in the mixer are
green, then the piano-roll data is for information only, unless you switch a section to "Playable RealTracks". Try this video if you want to use that 2022 onwards:
Using Playable RealTracks). It's value for composing is doubtful, IMHO ... probably better to use MIDI tracks.
If the track is yellow, then it's definitely MIDI and editing should work (unless the track is frozen). I think that's also true of MIDI Super Tracks.