I had this working on a development site several moths ago. The project was stalled and I'm now getting back to it. For some reason, it is no longer populating the tags blog we set up previously.
The last post is from May 2012. I have published several new test posts from a public blog, but they don't show up.
If I try the populate posts option in the network admin, I get either a 500 error or a blank white page. This happens with a single ID or with the "all blogs" option checked.
I have disabled all other plugins and emptied the mu-plugins folder but the problem persists. I have even removed and reinstalled it directly from the wp repository.
This is not on shared hosting and there are currently only 10 blogs so it's not a resource issue as far as I can tell. Can you please direct me in what to check next to resolve this?