I have the same issue. I have a series of payments starting next month, but the first payment is different to the rest. So I set up a one shot payment for next month, dated 1 June. I have set the recurring standing order for the different amount starting 1 July. Unfortunately in the section under “Scheduled payments & standing orders” I see:
Payment 1: 1 June
Payment 2: Monthly on 1st
So it looks like both payments will come out on 1 June next month.
Can you confirm that the 2nd and subsequent payments will indeed start on the scheduled date? If this is correct could you please request a UI update to display the post dated start date