Just updated and opened a solution. Thought that R# had just gone AWOL as it's prone to do these days. However I noticed a lot of disk activity and eventually it became available so I think on this occasion it just didn't show the usual 'Processing Assemblies...' stuff.
All in all my experience of the latest EAP versions has not been impressive. It seems like half the time R# just can't be bothered any more. Getting to the point where I no longer expect it to help me and that's only a short step away from uninstalling it and freeing up memory for something more useful.