I have a MacBook Air and my iMac. On my MBA, I saved a Keynote presentation to iCloud. If I use File>Open and click on iCloud, I see the document and the grey hatch background of iCloud.
on my iMac, however, File Open shows me my local files, and when I click on iCloud, I get about 1cm of grey bar but the rest of the dialog box shows my local files still. (The left drive bar disappears). One way or another, iCloud refuses to show up.
I deleted Keynote and reinstalled it, I went into System Prefs and turned iCloud Documents and data off and back on, didn't make a difference. Not sure what else to do.