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06/09/2010 - SIBELIUS 6.2 - WIKI software updated - Announcements

Bars with rests not included in adjacent multirests or a multirest inexplicably splits into two smaller multirests

Check whether the barline at the break is not a default type. You can easily do this by (in the score or part) selecting the top or bottom of any other barline, so that your barlines sprout handles.

If there is no handle on the offending barline, select that barline and press delete: it was a special barline of the normal type, and all special barlines break multirests.