Waypoint tier 3 bug

Possible bug or ui interference

Killed boss (serpent) still have 2 or 3 to go complete. Once I killed boss in area , the prompt to go back through is gone just a red barrier.

Steaming Springs
Monster lvl 67
SL
F4A
California Realm
>50 monsters remains

Buffs
+57% increased magic chest
+49% increased rare chest
Area contains rituals