Open Rule the waves 3, load game 2 save file, there should be one single destroyer ship on the fleet page, right click to open designer for that specific ship, go to graphics tab in the designer, select a detail object such as a mast, then click move layer up down a level, observe errors, exit out ...
Thanks. Are you able to reproduce this from a save?
Using this specific save I was able to reproduce the errors by opening the ship in the designer, selecting a detail part like a mast or something, then selecting move layer up down a level, I will be asked if i want to do it to the 0 and 1 ...