macmanx - hi - It seems to be working now, here are the steps I took:
Before trying Chrome I thought I'd try this using Firefox in private browsing mode. So in that, I went to petspeopleandlife.wordpress.com and clicking the 'Follow' button in the admin bar gave me the tooltip that I was following and would see posts in my reader, but the 'Follow' link didn't change to 'Following'. I then went to the Reader's edit page and this time it did appear. I then logged out of my WordPress.com account and out of private browsing mode. Logged back in, not in p.b.mode and blog still showing on Reader's edit page, but still not showing as 'followed' in admin strip on the blog itself.
I then closed the browser window and cleared cache/cookies and logged back in - not in pb.mode - and blog still in edit list. Back to her blog and it now shows that I'm following.
So, I don't know what happened there. Any ideas?
Just to be sure, though, I downloaded Chrome and it works in that too, both in normal log in and in p.b.mode (Incognito).
I'd like your opinion on what could have happened so that I can avoid it in future.
Ah, and there's another person with this same issue, on this thread: http://en.forums.wordpress.com/topic/cant-follow-blogs?replies=4#post-1163862
One other thing, which I find a bit odd, on the home page the image in my current post http://artyoldbird.com/2013/02/25/mountains-are-sort-of-slanty-sided/ appears in Firefox but not in Chrome. Yet the other pics in other posts are fine. I've put a screenshot of the two windows, tiled horizontally, on a page in my blog, here: http://artyoldbird.com/chrome-view-vs-firefox-view-temp-page/