Septuplet uses too many beams.
Create then select a quarter rest in a x/4 time. press ctrl+7 to subdivide into a septuplet. Fill with notes. Result beat fills with seven 32nd notes. You would expect the beat to fill with seven 16th notes instead since the 16th note is the next higher note value. Said another way: the ratio of actual notes to the number of regular notes should always be between 1 and 2
Comments
Alfred's Essential Dictionary of Music Notation basically confirms what MDMilford says above but mentions "Duplets are the only exception.... Duplets are equal in rhythmic value to the beat (not to be confused with pulse). Duplets only occur in compound meter" ("Tuplet", p.159-60). In other words duplets should have a 2:3 relation (which MuseScore already does correctly).
As a workaround you can use Notes > Tuplets > Other... and specify a 7:4 relation for the example you cited in the original report. (Tested using r. 2781 nightly build, Windows 7)
fixed in r2833
Automatically closed -- issue fixed for 2 weeks with no activity.