Also bumping this up as it still seems to be a problem in RC15 (though it is really just a visual glitch so not so important).
I've included a picture this time to show the issue when toggling on and off Free Port with Light Industry:
Free Port off:
Spoiler
(https://i.imgur.com/kjsxrZl.png)
Free Port toggled on then off again:
Spoiler
(https://i.imgur.com/zYkLGgp.png)