Lights not able to be placed as shown in mod images

[Maltshakes]

I'm trying to connect strings of lights to slabs as shown in your images, but the lights refuse to place. They will only connect to the underside of a slab like so:

For comparison, here is an image from your mod page, showing lights attaching to the sides of slabs. Do they no longer connect like this or is there some trick to it?

I'm using Fairy Lights 4.0.5-1.16.5