Bar stretch and reduction

Since the last update, 3.0.4.21117, I am finding that some bars spontaneously extend horizontally across the score to a notional point perhaps three pages away to the right. Trying to reduce this effect by the command shift { to reduce a bar length on the page, actually does the opposite, and extends the bar further Brigg Fair 3 SATB.mscz . Command shift } has the same effect. Going to bar properties and altering Layout Stretch has no effect either.