No portals in mirage

I'm currently running elderslayer in city square maps with maven witnessing. After i defeat the elderslayer boss in the mirage no portal appears to go back into the map so i have to go back to the character selection screen otherwise i'm trapped in the boss area. It only happens when i'm fighting the elderslayer in mirage. This is a consistent bug and i haven't been able to get back in the map since i've been running this strat.