Not sure what is so special about this tile, the mountains, being stuck between two locations, but the tile yield is not showing on the map.  It shows in the popups as buildable and I did build on it.

Also, playing as Tarth, I am still getting attacked by monsters.  It is probably just them wandering randomly into me, but it seems odd to say you won't be attacked and then get attacked.  Perhaps that trait should only be "will not be attacked by beasts/twisted/dragons"  That way bandits, etc will still attack.  I don't think they should care how much you commune with nature.