Possibly MMs have changed their programming for this type of trading when there is no significant retail action to push prices either up or down?
Just grasping at straws, I guess.
Edit: MVNT wasn't even listed on FINRA's daily short volume list yesterday. Perhaps they don't list tickers that have ZERO short volume?? (Doesn't seem to be the case. see link below)
Perhaps they don't report a number if short sale volume is less than 100 but greater than zero? IDK. Doesn't make any sense why no data is shown for MVNT yesterday.