Go to the BP_QuickSlotsPanel widget and create a new function called FindActionMappingKey.
Add a new input to the function called Input Action and set its type to InputAction
Add a new output and call it ActionKey and set its type to EnhancedActionKeyMapping.
Create a new variable (Not a local variable) and call it Mapping and set its type to InputMappingContext and set its Default Value to SGKCharacterInputs
Add the highlighted nodes shown in the image below, location at the top of the image.
Replace the code your currently have this the code shown in the image below, location at the top of the image.