Mobs seem to "wrap" around the edges of blocks when taking a path to the player, even when there is a straight, direct path to the player. This happens in a flat area with no hazards between the mob and the player. It seems to happen when the player is within a few blocks of the edge that the mob is walking along. The issue is that the mob shouldn't be winding along the edges of blocks if those blocks do not obstruct their path to the player and if there are no other hazards along the way. The screenshot displays this behavior; the zombie has a direct path to me but instead chooses to walk along the edge of the blocks to get to me. I tried searching for the issue but didn't find anything that matched it. Not sure if this behavior is intentional or if it is just a false attempt to take a safe path to the player when there is no danger in a direct path. The path a mob will take when near a hill/wall becomes a bit unpredictable and makes combat in that situation less intuitive as the mob will not have attacking the player as their primary objective. I don't like to mess around with using snapshots, so I don't know if it is still an issue in the latest updates. It's difficult to get decent screenshots that display this behavior, but using a similar setup will help with reproducing the results. It definitely seems like the mobs are trying to take a safe path when it isn't practical/needed, but I can't say for sure.