World edit grid lock issue

Ive been making a map and recently a file got corroupted so I had to restart, so as I was remaking my capital city out of no were when I click Ctrl to snap teh new building to the grid it turns invisible until I release the key, leaving me cluless were the object ends up. Ive tried not using the grid but all ive got now is a city with unalind buildings. any idea how to fix?