maps resets and hide all check points and whole map

I recently did a fortress map and died on the final boss. So when i went back to try again the whole map I opened up clouded back over and I resed at the beginning of the map. It suck having to run all the way back to the boss and to reopen the map again even though there is no mobs left to kill. I don't know if this is a bug but once you open the map up and can see all the areas it shouldn't reset when you die.