First bar won't join multi bar rest

My first bar has no rehearsal marks, text or chord symbols (that I can see, I have all sign posts on) yet I cannot get the first bar to join the following 3 to make a 4 bar rest. Please help!

We’ve Only Just Begun Key of Bb.dorico (612.4 KB)

For some reason, the first bar is eight quarters long. Re-input the 4/4 to turn it into a 5-bar multirest, select it, type Shift-B, -1, Enter to get rid of one bar.
As to how this 8-quarter 4/4 bar came to be, I’m not sure. Was this an XML import?
edit—welcome to the forum, by the way! :slight_smile: