You might be missing a GBOwner node. Added to where the players placement authority should exist (whether its the game character or the god hand placing objects at runtime). You could add this to the GridPlacement and set the GridPositioner2D as the owner root.
If that isn’t it, double check your injection root on the GBInjectorSystem. Ping me on the discord. Thanks :) 6.0 is going to solve a lot of this node structure setup complexity. Actively trying to get it ready for publish soon.
The errors tab where it says (18) and (23) in red might have more revealing information as well.