In 1.8.1 it appears that if you open a map which was looted in 1.8, it changes the EP of the loaded level to that of the previous map you were in.
Example: I had a lvl 361 EP2 map (looted in 1.8) on my hireling. I finished lvl 360 on EP7 on my main. After killing the cartographer, I opened the lvl 361 EP2 map and it loaded a lvl 361 EP7 map instead of a lvl 361 EP2 map.
I experienced this during the test patch in the opposite direction, showing lower ep. Are you sure it isnt just graphical, cause my m3 maps sure didnt change to normal difficulty even though it said they were when I opened them.
Yes,I normally do not have access to Mythic3 floor 500+. By using this bug I now do. I even bought a map from said map. Now I have 2 500+ mythic 3 maps. I have plenty of 1.8.0 maps left to try other defficulties later.