That's a Deciler map, I believe. Even in vanilla YR it does that... I spoke to Deciler about it ages ago and he scoured the map for hours trying to find what caused it to no avail. :( Not a lot Apollo can do about this one im afraid.
Oh, and the Hex map crashes after a bit. Makes the game lock up. :\
That's one of my old maps (I am Deciler), I seem to remember a few people saying this but I could never replicate the problem. Do you still have it by any chance?