Hi there, thanks for the reply!
I've not uploaded the project previously as it's pretty big and has many other things in there. I've truncated a copy of it with just the things needed in regards to my issue, link below :)
I have already checked in debug mode, the instances don't get the variable changed for some reason. I've also tried to force them to change on mouse over the mapSquares. The square maps are created at startup over the tilemap as you'll see. I've also removed the "for each" conditions from mouse over actions but still did not fix the issue.
The layout has a 9-patch at the bottom (the "frame" of the map) and 2 instances of the same tilemap as stated previously. The UI General sheet is the one you want.
Thanks very much in advance for any insights!