I have an existing Yosemite installer app from the original release of 10.10 (e.g.
Install OS X Yosemite.app) but can't seem to download a newer installer. When I click Download, I'm presented with this dialog:
However, clicking Continue doesn't appear to do anything. No update appears to be in progress, no network activity shows in Activity Monitor.
The same dialog appears if I click the Download button in Purchases, and the download never begins.
How can I get an updated installer?