I’ve had some weird issues when messing with BlueprintInterfaces after I defined some stuff on inherent blueprints. Try this:
- If you’ve changed some function definitions AFTER you placed nodes that call that function - right click on function calling nodes and refresh them.
- unhook every execution wires TWICE. I’ve had errors telling me that some nodes can’t have two inputs/outputs while I could clearly see that the node had only one. After I held ALT and double clicked every exec pin - problem solved.