No experience points are gained.

      "everfrost tonic": {
        "displayName": null,
        "shortname": "xmas.present.large",
        "skinID": 3646162060,
        "effects": [
          {
            "min": 1.0,
            "max": 1.0,
            "duration": 3600.0,
            "biomes": [
              "Arctic"
            ],
            "timeRange": null,
            "source": "All",
            "type": "XPBoost"
          }
        ]
      },

Players have reported that using the following items prevents them from gaining experience points.
Experience points are reportedly gained normally once the potion effect wears off.
Do you have any idea what might be causing this issue or how to resolve it?

VERFROST TONIC[+100%-ALL[3600S]-ARCTIC