During a combat, a monster come to a character and stands around a corner in the wall (an outside corner) and melee attacks character. Characters turn comes, and they are unable to melee attack the monster around the corner, but can melee attack another monster so attacks other monster. Monster around the corners turn comes and it melee attacks the character again. Another characters turn (They are diagonal to the monster and first character, so the monster is still around the corner to them) and he does a distance (bow and arrow) attack on enemy around the corner. The first characters turn comes, and they attempt a melee attack and is unable to see target still.
This has happened about repeatedly while fighting against different monster types. I am not sure if this is really a bug or possibly a weapon type issue. First character was using slashing weapon and Second was using piercing, I am not sure of the weapons used by the monsters around the corner, but since it happened multiple times they were probably using various types of weapons.