My ritual diviner dusk does not place any blocks. This means I can't do anything else. I've been sitting there for 3 days, can someone please help me

I know it's likely we'll never hear back because it's been, uh, a year now, so i'm pre-emptively closing this, (because this issue does not seem to be replicable in any of our tests) but on the off chance:

Are you playing in single player or on a server? What mods are you playing with, if any? Are you 100% certain that there are no blocks in the way of where the ritual wants to place its blocks?