MU 4.0.1: Numerous bugs with parts, including show-stoppers (major).
View the parts.
1. (minor - workaround) When parts created, the "zoom" is set to 0%. In the attached file, the zoom on the saxes and some of the rhythm was set to 75% before saving. If it is not 75%, then the current zoom on each part is not saved and probably should be.
2. (major) The Alto 1 part lost the voltas on the first repeat; the other parts that I checked have those voltas correctly.
3. (minor - workaround) In the saxes, the multimeasure rest in the first repeat was overly compressed horizontally (I fixed the baritone part, but the others still show the over-compression. (Being able to so compress a multimeasure rest should be an option via decreasing stretch, but not a default choice.)
4. (major) The chord symbols did not transfer correctly to the part. This can be seen in the 2nd Trumpet, guitar, piano, and bass parts.
5. (minor for now) In the drumset part, I could not find a way to decrease the space between the paired staves. For the part, I reduced the minimum distance between staves (Style->Page-Min. Staff Distance), but saw no effect on the part. I think the algorithm to place the staves should keep the staves in a system as close together as possible (limited by the Min. Staff Distance option or the notation), regardless of the spacing between systems.
6. (minor for now) Again in the drumset part, for the last two systems in the part, the rehearsal numbers and the voltas leave room for the hidden staff.
7. (minor for now) More easily seen in the drumset part, the "Repeat last two measures" only marks the first of the two measures as used. See measures 48 and 50. This can also be seen in the full score.
I'm not sure that the three designated as "minor for now" are minor since I found no work-around and I'm not sure that the parts should be left as they are now.
Note: I find the idea of the second staff - in this case a 1 line staff with rhythm hints for the drummer - very useful. In particular, I find the option to hide empty measures extremely useful.