“On the chart they will be shown as red volume but is this because your data feed recognises them as originally short orders now hitting ask at market to get out? ”
The “red bars” are actual DM short positions. So these are open positions (on the historical histogram you can also see the ones who were already kicked out of the market).
If positions are closed, the respective position bars disappear from the “current DM histogram” / the y-axis.