My mistake. it’s the ‘Official Twitter Plugin for WordPress’ according to the plugins page, and on the details page it says it has not been tested with the current version of WordPress; that must be the issue. Unfortunate, I was very happy with the way it worked and haven’t been fond of others I’ve found.
Hi, thanks for responding. It turns out it was just me not being thorough; for some reason either WP or my theme was no longer linking to the file by default, so I fixed that and now everything is back to normal, it wasn’t the plugin at all!
It is a managed WordPress plan actually, yes. So based on your information I’ll just wait until tomorrow and see what happens, updating this thread as appropriate. Many thanks for your input.