ActionGraphs no longer load in editor after adding custom node and saving

I’m trying to develop a custom OmniGraph node. I’ve made a distance into this, but suddenly, after saving a graph with my node in it, I can no longer open the editor. My only clue, is the following error in the console:

2023-01-10 03:15:15 [Warning] [omni.graph.core.plugin] Stage contains OmniGraph ‘/root/ActionGraph’ using schema prims but schema prims are disabled. To enable the graph turn on the ‘/persistent/omnigraph/useSchemaPrims’ setting and reload the stage.

I have no idea where this setting is or how I might change it. Searching on the web doesn’t return any hits.