Is PlayerRef a Pawn, a Character, your PlayerController?
The ArmourActive? boolean, how is that assigned? Does that only exist within your widget?
The ItemData members of your Inventory array, are they structs?
Where is the Inventory currently stored? Is it part of you widget?
What does the SetArmour method look like?
Is this structure based on a template, or tutorial, or is this your custom creation?