Musescore 3 - Guitar LH fingerings disappear from bars when I try to reposition one fingering

I'm finding that if I try to slightly reposition a fingering number, some fingerings disappear from the bar below it.
In bar 8 of my example file, if I slightly move the first '3' in the bar (i.e. the C-sharp's below 'CVII', some fingerings in bar 10 disappear.
This happens in other places also.
Example file is called El Guitarrero MH