https://i.imgur.com/cMRoAdh.gif
The action works perfectly, creating a new track beneath the selected track. However if you undo and redo, the newly created track takes the place of the track below it
and erases what was on it. Further more, it shifts the names of all tracks.
In the licecap, I draw your attention to the Snare track under the one that is solo'd. Also strangely at the bottom the MIDI from the penultimate (yes...used that word) track is moved up o.0 and replaced with the last track's MIDI.
Some strange things going on here!