Still waiting

I love this game sooooooo much Ive beaten every boss in the game but I cant fight the cultist Ive beaten golem plantara and dukefishron and after I kill them I go to the dungeon and hes not the I dont know if its because there has not been and update or its a glitch I play on a iPod touch iOS ????

Lil nug2 about Terraria, v1.2.12785