That's very, very interesting considering the stones are working just fine in the US (I just tested to make sure), and it might have something to do with the fact that the EU patch is roughly twice the size of its US counterpart, according to a couple of people following our Twitter feed. Knowing very little about how these things work, my initial assumption was that the size difference was due to extra weight on the patch for localization purposes, but that might not be the case. It's possible Europe just received a few changes that we hadn't yet, and that's what's causing this. Or maybe not. We don't really know, and anymore speculation on my part would just make me look pretty silly considering I know so little about the process.
We may not know what caused the issue, but we do know one thing: Your party will need to hoof it to their dungeons for awhile, old school style.
Update: It appears the meeting stones are now fixed, and didn't require a restart or maintenance period, either! Hooray!