Sorry for resurrecting this thread, but thought I’d just add that this works for me in UE5. Not sure if it has been a recent addition, but here is my USTRUCT inheritance structure that works fine.
USTRUCT(BlueprintType)
struct FInventoryItem : public FTableRowBase { GENERATED_BODY() }
USTRUCT(BlueprintType)
struct FInventoryItemEquipment : public FInventoryItem { GENERATED_BODY() }
USTRUCT(BlueprintType)
struct FInventoryItemWeapon : public FInventoryItemEquipment { GENERATED_BODY() }