Deleting a Category that is referenced in a ItemSetRules scriptable object that is referenced from InventoryItemSetManager will corrupt the InventoryItemSetManager. I think there might be a bug with how InventoryItemSetManager mantains this information internally.
This stops the ItemSetList from loading, for existing valid Categories in the InventoryItemSetManager.
Workaround: To fix this, I had to edit the ItemSetRules in debug mode to remove the broken Category. Then remove the reference in InventoryItemSetManager and add it back in.
I looked at other posts and I don't think this issue has previously reported. Apologies if it has and this is a duplicate.
This stops the ItemSetList from loading, for existing valid Categories in the InventoryItemSetManager.
Workaround: To fix this, I had to edit the ItemSetRules in debug mode to remove the broken Category. Then remove the reference in InventoryItemSetManager and add it back in.
I looked at other posts and I don't think this issue has previously reported. Apologies if it has and this is a duplicate.