Hi E847,
The issue lies with how you are setting the rotation of your decal component. If you get rotation at a distance along spline the decals will orient themselves along the spline. It looks like you simply want the decals to be aligned along the floor so unplug the rotation input in your “make transform” node and put 90 in the y value. You can try x or z if that doesn’t work but I’m pretty sure it’s going to be y. That will align your decals up and down relative to the floor, as long as the Blueprint’s orientation remains at 0,0,0 in the scene.
I hope that helps,