The bone spear bug was found relatively quickly, but it was either not trivial to fix or not considered serious enough to give it priority over other bug that were fixed.
Sometimes a BF dungeon entrance can be partly or completely obscured by a wall. Check the auto map, to see if you can see some blue sticking out somewhere. Running around methodically searching with the mouse can also help.
Occasionally the entrance can be a pile of rocks, rather than the usual fountain thingy.
