If you could look at the video i posted before, i will try to explain my situation with this. During the time 10.14', the guy starts rock smashing the first three rocks(i believe he smashes only the one at the right corner), so i did(i have also tried smashing all three of them, but the result was the same). Then i proceed at the floor bellow. At 10.56' he does the same on the next floor, where only one rock exists. In his case, there is no encounter with a magcargo, just the notification needed for the lava. For me, however, there only the encounter. Finally, at 11.15' he repeats the same process at the next floor, which i did and it is the only one working for me. I even tried to clear the above rock again after the one i last mentioned, but the notification just won't appear.