OK, then of course the vertex snap does not apply here since it is found in the A6 WED. Two things to look at then:
1/ When you initially place the blocks, make sure their position offset is large enough so that they separate a little.
2/ read up on "bounding box" in the manual. That will explain when there can be a problem with the bounding boxes.

Those would be the first two "simplest" things to check.