aSkyblock Island Level Prefix not working

I looked it up online and if you added {ISLAND_LEVEL} in the prefix of a player, it would show your island level in your prefix. However, when doing exactly that, it didnt work for me. Also nothing showed up in the console so I have no idea what to do. The prefix looked like this for players , [lvl: {ISLAND_LEVEL}][Member]:

Can someone please help me out if you know!!!