Hello again ,o/

Sand layers don't stack when manually placed in creative, like snow does. That's pretty much it. 🐢
Not sure if they're supposed to stack, though.

I'm trying to fill up the portal structure hole.

What Forge version are you using?

There may be some issues with block placing in some newer version of Forge, but they should work in the latest version of Forge. At least it works for me.

Yeah, that must be it. I'm using 14.23.5.2823 currently for testing, but I'll downgrade eventually.
Thanks 🐢

It might be broken there, but should work in 2824 :)