Reducing stretch corrupts (?) score with clef change

Windows 7, GIT commit: 5363f93

1) open attached score
2) position so you can see last two systems; note there is nothing below the bass clef staff in the last few measures
3) select all
4) reduce stretch three notches ("{ { {")

Result: somehow, a bunch of notes appear to have dropped a couple of octaves or more - they are now several ledgers lines below bass clef staff. Actually, though, they aren't lower in pitch when you play them back. They are just being displayed as if they were in treble clef!

For instance, here is the last measure of the piece as it looks originally upon load:

And here it is after three notches reduction in stretch:

The note below the bass clef staff was supposed to be an F, second line from top. It now displays three ledger lines below the staff - which would be correct if this were treble clef. I can't see any pattern to which notes are affected, but it's not just this note - there are affected notes in most of the last seven measures.

This is not the only score that exhibits this behavior, BTW. I see it also with "Reunion". I guess it probably has something to do with there being a clef change.