How to remove any "hidden dynamics"? [solved]

The MS project at hand was imported from a MIDI file. That MIDI originated in the Reaper DAW sequencing software I use, as an export. In Reaper, I made dynamics changes to various parts and sections, but such was not done "notation-based" (i.e., 'F' versus 'MP').

Now in MS, I find dynamics changes where no notation-based markings are present. I've removed ALL notated dynamics, but still, during playback, there are volume changes (most noticeable in the last 8 bars or so).

I've looked into the MS "piano roll editor", and wonder if I can use that to set all note velocities to one value, to get rid of any hidden dynamics.

Suggestions? Thanks.