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