When playing today a shark attacked my foundation and destroyed it. No big deal. I went to repair it but noticed I was unable to do so. It appears the game thinks that a foundation is there even though it's not. It's not a visual thing as I was able to fall through it into the water, and I was able to place foundations in other spots aswell.
Here are some screenshots to visualize my somewhat poor explanation; http://imgur.com/a/Iolin.
Keep up the great job on this game. I'm loving it so far!