I've placed a block inside a rectangle. I can make dimensions from the rectangle to the block. However, when I change those dimensions, instead of moving the block, the block is rotated. Why is it rotated? How do I tell SE, "Don't rotate my blocks"?
Think of the block occurrence as a unit of geometry. Inside of the block you may have horizontal/vertical constraints, but those constraints are only active when editing the block. The Block occurrence can be manipulated (moved, rotated, etc.) just like any other piece of geometry. Therefore the block is free to move. you can lock down rotation by adding a horizontal/vertical constraint to one of the lines. Do this on the block occurrence, not in Block Edit. Depending on how much is constrained, you may have to delete one of the dimensions to the block first. Once you lock down rotation, you cannot drive the position of the block from both directions. This is overconstrained.