Problem creating parts from midifile in MuseScore 4.0

Attached is one of the midi files I tired. Three images
1 the midi file loaded into musescore4
2 the parts button pressed (I would usually rename the parts p1///p4 but problem same if I don't)
3 openly the parts. Each just contains rests and tempo info. No notes.

I want to export individual uncompressed musicxml files for each part separately. No good if the parts contain just rests.
As a workaround I delete 3 parts in turn and exported the remaining one in the main file. Then undid deletions and repeated retaining a different part. Works, but tedious.