Originally posted by Florelit:

Originally posted by Bricks:

I do have the same issue with the Ancient. The mark on the map is given but there is no altar or the well known arena :/

You can use the boss stone that made that mark once again - the new correct mark will appear. Old one could be replaced by right click

Thank you very much, Florelit! That worked well after removing the old position by right click and seeking out for a new boss stone.