Working on a measure like this:
The flat sign on the fourth note of the sextuplet aligns vertically with the third note of the sextuplet. That looks odd to me in general, and in this case it is messing up the slur. The slur is attached only to the first three notes of the sextuplet, so the end of the slur should be much higher, near the Bb4 notehead – which is where it moves if I manually adjust the horizontal spacing in engrave mode.
To prevent having to adjust this all manually, I can set the minimum spacing for small notes, though I’d prefer not to do that since it affects cases where there isn’t an accidental. Is there another setting that would affect the spacing to better account for the accidental? (All spacing, etc. is using factory defaults.)