Doubly implied constraints in Knowledge node

[Scott]

If you imply a constraint by creating a forbidden group, and that constraint is also implied by tiers that you specify, you can save the node and as far as I can tell it will run work OK, but the Knowledge node can no longer be edited.

From then on, every time you click the Knowledge node, you get an error: "That edge is already in the graph" (with details about the first edge that had been specified twice), but the node never opens up for you to make adjustments.

You then have to delete the Knowledge node and re-specify all of your constraints.