Periodic extra blank in between-systems spacing

[PMA]

Dear LP List,

I've drafted a score for solo piano.  Its systems are of two types: either a PianoStaff (with the usual 2 internal staves) or a single independent Staff.  The systems are grouped into separate \score[s] by type -- i.e., each contains either PianoStaff[s] only or independent single Staff[s] only.

Within each group, between-system spacing is normal and consistent.  However, whenever the system-type *changes* (i.e., between the last system of one group and the first of the next), LP inserts a *staff-sized blank space*.  (This occurs even if I remove the multi-\score framing.)

So my question: How can I remove that space?  Thanks in advance for your consideration!

Peter McKenzie Armstrong

(See attached one example page from the output, as JPG.)

PMA-p3.jpg
Description: JPEG image