This widely known bug is caused by an "overload" in your save file that is saved at EA's side. Essentially, you can say your data is "partially corrupted" though it is entirely functional. Try avoiding customization and reset settings such as "World Option" with the reset to default buttons and it may solve this though unlikely. This appears to be a problem of EA as it seems the server can not store the save file properly when it has more data. It is best to wait until the next patch when this would be fixed though no release date have been confirmed yet. Sorry!
-VoltScience: Exposition Mage
