ah-ha. it's also a "web" document which is known to have issues stretching things horizontally only. if you change it to "print" then you can select the group in page and layer gallery and it'll properly stretch everything by just the middle handle too. if you wanna keep it "web" template then hold alt down while dragging the middle handle horizontally to keep everything exactly as the example.xar file is and to stretch everything horizontally by selecting it in the page and layer gallery

project should be started using any template other than web page or photo