Measure Lengths changing when exporting to mxl

I'm working on cleaning slightly corrupted files, Musescore version 3.2.3.22971, macOS Sierra 10.12.6. The file in question had multiple measures with added beats of rest, e.g. a bar of 9/8 with an extra eighth note tacked on to make 10/8. I've been cleaning the file by hand, right clicking problem measures, clicking "Measure Properties" and then adjusting the actual number of beats in the measure. The problem is that when I export to .mxl, the changes I have made don't stick, and the .mxl file contains extra beats in it, even though the original musescore file from which it is formed contains no extra beats.

Below I've attached my musescore file, as well as the problematic .mxl export. An example of my problem can be found in m20 in the .mxl.

Please let me know if you need more information. Thanks!