Clef change flakey in part starting with multibar rest

Using Windows Nightly 93e1d5b, running in Wine/XP

Steps:

1. Create a single part (from a printed score), using the original transposing treble (G) clef. The part has four bars rest at the beginning.

2. Via General Style, allow multibar rests.

3. Change the clef to alto (C) clef, either by dragging clef from palette or selecting first clef and clicking palette clef.

Expected behaviour: all clefs should change to alto clef and notes move to appropriate position on stave.

Actual behaviour: all clefs change except the one on the first line. However the notes still change position on the stave to where they should be in alto clef.

Comment:
If I change clef before allowing multibar rests, the clef change works normally, and sticks all right when multibar rests are allowed afterwards. So maybe it is a 'feature' rather than a bug - rather disconcerting, though.

I realise this may only be a problem in XP, which is not supported.