Last Visit Time Not Updating

Can be demo-ed on Area51. Over on Area51 it says my last visit was back in February. This is incorrect, as it should be showing a date more like yesterday. I've even logged in many times since February, which also should have reset the last visit time too, at least.

On phpBB.com we still see the correct last visit time displayed.

Other users who have reported on this also show times from February, even December 2014, even though they have visited much more recently.