OK, after having to put this down for a couple of weeks I've come back to this today and done a clean install with the new version of the AT.
I haven't tried previewing a course yet but I thought I'd query another problem I keep having, which maybe related.
The last four or five times I've installed the AT, when I try to load it in my browser the AT starts to load but doesn't get as far as the login screen. It just sits with the loading spinner showing. A check in the network log shows that origin.js has failed to load.
With previous installs I've just gone and added origin.js to the appropriate place and then I've been able to login and author. But I wonder if this is in someway related to my preview problems.
I'm not sure why origin.js is missing. I've installed the AT by cloning from git and by downloading the zip file from git. Same problem either way.
Before I manually add origin.js again, does anyone have any ideas why this is missing?
Thanks,
Nick