Current diff should be around 12 T

The diff for open-ethereum-pool based pools is given by the backend stats api.

^{"nodes": [
  {
    "difficulty": "12007813457252",
    "height": "1205495",
    "lastBeat": "1507744542",
    "name": "main"
  }
]}

Check your backend configuration!

Have you made the UBI update yesterday?