So this happened in the very first dungeon. Revisited it at about level 10 and was running through it at legendary difficulty. After passing through a few areas, I noticed that pressing the “m” key to bring up the map no longer worked. Also, when approaching a chest which I hadn’t opened before (was still sparkling), the “e” key prompt was no longer appearing. And when I tried pressing the “e” key, I couldn’t get the chest to open.