Mid-measure barlines are not exported to musicxml
See original discussion in https://musescore.org/en/node/281471.
In measure 1 I have selected the first note after the barline and double clicked the appropriate barline. This is not exported to musicxml at all.
In measure 2, I have press ctrl+drag the same dotted barlines as measure 1. The measure split as hhpmusic requested, but the barlines are solid.
In measure 3, I have used measure 2, selected each measure section and double clicked the dotted barlines. The barlines are now displayed correctly and the measures are split.
The expectation is that the first method should export properly to xml and indicate that the measure has been split x2 then x3 and so on. Measures 2 & 3 is a different bug which I'll report later.