[Imp]

Have you tried cuting & pasting the entire map to a new map using the advanced map editor to see if that fixes it?
Could try pasting to a slightly larger map also to see if that fixes it & then trim or not taking the first few hex rows.

Also adjust the way you do things slightly to see if that solves things.
Veiw adjust & save the map BEFORE buying reinforcments rather than after, I have had no issues doing this.