If you have CIS setup correctly in QBO & have used CIS Labour (20%) on your invoice for the Labour element it should do this automatically. The amount due in QBO will be £255.90 (with £43.00 CIS deduction expected).
Presumably, you were expecting the 20% CIS deduction on the labour (you are registered for standard deduction, not gross status)?
You also mentioned Reverse Charge VAT (which would be £nil) but you have it calculated at 20%. If the client is the end-user, Reverse Charge does not apply - use S20 code instead.