Holes appearing in terraforming

After building and logging out / in holes appear that others can’t see without logging out then in again. The holes can be filled in but show up again after logging.

Locations
Zone 979
623-473
537 – 369
633 – 338

Zone 979
623-473

Holes keep showing up in this wall. One guy can see it, the other cannot. It reappears for both after filling in and logging out / in.

http://img715.imageshack.us/img715/1...1071117850.jpg

Zone 979
537 – 369

Again, one guy can see it, the other cannot. It reappears for both after filling in and logging out / in.
http://img688.imageshack.us/img688/3...0711171351.jpg