When a unit happens to be in the lower left corner of the screen and you mouse over it, you get a popup with the unit info.
That popup covers the unit and you cannot attack or otherwise access it.
Yes, you can scroll the map and try the same thing again all over but that should not be necessary.
If a unit is within 150% of the area, that the unit popup covers (you sometimes need to access the area around that unit), then
the popup should instead pop up more towards the middle of the screen.
