Selecting Dive (Mirefolk Stalker) correctly highlighted all water spaces within 6 tiles. Selecting a water tile that was a default water tile with impeding 1 just wrote "invalid target" to the combat log. Selecting a water tile with generated, non-impeding water worked fine. This was on the map with the little rivers you have to cross to get to the two fonts near your shrine. I was diving from the shrine deployment zone on the top of the map to a tile in the nearest font.
Check to see if something can tunnel vegetation etc. there. Might not be labeled as a water space. Your comparison was generated so it wasn't map specific.
