How do I flip multiple wrapped sprites in the layout editor?

For example, if I've set up a room in a dungeon, with switches and enemies and paths and holes, etc., but realized I have to flip the entirety of the room along the Y axis, is there any way to do this without going into each sprite's width and making them negative?

Like this:

The only way I know is to turn "Snap to grid" on, select all sprites, wrap selection. And then flip by resizing, making sure that the final width of the wrapped area is the same.

The only way I know is to turn "Snap to grid" on, select all sprites, wrap selection. And then flip by resizing, making sure that the final width of the wrapped area is the same.

I've tried that but for some reason the sprites start extending in all sorts of weird directions.

Did you do this?

Did you do this?

Yes, that's what I do. This is what happens:

I'm guessing your sprites (small boxes and walls) have origin image points not in their center.

When you wrap them and flip, each sprite is rotated 180 degrees around its origin point and this mess happens.