can confirm for 1.18 pre-release 5
confirm for 1.18 pre-release 4
also, you can use them as normal blocks and stand on them in survival mode and if you use the keyboard buttons instead of mouse buttons then you can create a big giant line of ghost blocks without needing support
This is in 1.18 pre-release 3
you can also by the way move the ghost bocks around by right-clicking while holding scaffolding in your main hand which is pretty weird.
I posted my videos to check that out
this is also in 1.18 pre-release 2
By the way, the floating scaffolding disappears when you leave and re-enter the world but still, it is not supposed to happen while playing
Mojang knows about this report but still hasn't fixed this for some reason.