Short Version:
1. AI players can move units into the same tile as a monster unit.
2. AI and monster units sometimes show up between 4 tiles.
 

Long Version:

1. In the Strategic view, were I to attempt to enter a tile with a monster (or even friendly AI player's) unit in it, it would prompt me to attack that unit.  If I were to use pathing to move beyond it, my unit would move around it.  AI players, however, can move their units into the same tile as a monster, with no combat.  I don't know if they're moving through or into, but the two units aren't attacking each other, instead sharing tiles.

2. In the Strategic view, sometimes a monster or AI player's unit will show up in the center of 4 tiles, leaving it to guesswork as to which tile it's actually occupying.  The screenshot is below, but to describe it, if you had 4 tiles forming a larger square, with the one shared point as the center, that's where the unit is standing.  Trying to select it doesn't do much to help, as the box appears around where it appears to be, rather than around the tile it's actually occupying.

Screenshots:

1. Notice how the unit that's selected is different than the one in the tooltip.  Both units are in that tile.  This shouldn't be possible.

2. Which square is the scout on?
 

I don't have savegames for either of these, although saving/reloading fixes #2, so a savegame wouldn't be helpful.

I should also note that neither of these are new problems.  I've been seeing both of these as long as I've been playing FE, since January.  They do not occur too often, but often enough to warrant reporting them.