XPBoost

Hello. When XPBoost is activated, players can use it normally; however, it disappears after they rejoin the server. Here is an example configuration: "XPBGr1": { "shortname": "xmas.present.large", "skinID": *******, "effects": [ { "min": 0.5, "max": 0.5, "duration": 3600.0, "biomes": null, "source": "All", "type": "XPBoost" } ] }, Could you please tell me if there is any way to fix this?

In other words, if a player leaves the server or gets disconnected, the boost is gone upon rejoining.