Pages 5.5.3: Cmd-W freezes Pages

I'm finding that closing a document with Cmd+W always freezes Pages (v5.5.3 (2152)). The computer is a mid-2014 rMBP (2.6GHz Core i5, 16GB RAM, 250GB SSD) running Yosemite 10.10.5.

The freeze behavior is as follows:

1. I press Cmd+W
2. There is a pause of roughly 1/2 to 2 seconds
3. The spinning beach ball appears
4. Pages does nothing further until I force it to quit

The freeze does not occur when I close a document by clicking the red "X" button at the window's top-left corner, so I try to do that. (Cmd+W is an ingrained habit, though, so I've triggered this freeze at least ten times by now, despite knowing not to press Cmd+W.)

I've cleanly closed Pages and restarted it since the problem began; I've also rebooted the computer since then. I usually have a bunch of apps open, but the problem has occurred when Pages was the only app open too.