I should have seen it coming

Well, that's it. Yesterday I found out that I had been overlooking the enemy navigation (I wonder how comes I had not seen it walking through obstacles before), but when I went to add the navigation mesh to the tilemap there was no way I could get it done. 

I considered many things to fix this aspect, which is quite annoying and gives the enemy a clear (and unnatural) edge over the player, and I have decided that for the time being I will make the enemy shoot the player rather than chasing him. This might result in a clear edge for the player, but in case I have two more days to arbitrarily complicate the player's life (and mine, of course)