Bizarre Twitter Problem

Okay, here’s one to make your head spin.

I have a plugin which puts up social sharing buttons on my site: http://www.triplepundit.com

The twitter counter, however, is always zero. So I changed the plugin to a different social sharing plugin. Same problem. Everything else counts fine, but Twitter count is always zero. This only applies to posts made in the last week or so. Older posts seem to have counted fine.

So…. I suspect this has to do with something on the site, and not the plugins.

Any clue what’s going on? What I might have done in the last two weeks to skunk Twitter? Does anyone else have this problem?