With the new update came this bug that me and many others are facing when trying to access a dungeon
Hey, thanks for raising this to us. We're currently in a call investigating this issue, it appears to be related to an engine update which was released today.
The fix might involve a reboot, we're not sure when it'll happen so keep an eye on the game status page for more information (https://secure.runescape.com/m=news/game-status-information-centre?oldschool=1 ).