Immigrationboards.com

Hi, my 19.5 years old son missed to ask for his passport to be stamped when he entered the UK.
Now, on his immigration application we stated the day he entered but apparently it is mandatory to have that stamp. I have to mention that we applied under the EU Settlement Scheme with me as his father already having the settled status. Supporting our case we have provided the flight ticket, boarding pass and written confirmation of the airline company that he boarded that flight.
Can you please advise what steps should we follow?
Thank you in advance

Missing stamp is fine, as long as you can prove he entered the country with tickets and boarding passes. I.e my wife entered the UK via Guernsey (Channel Islands) and she didn't get a stamp. I provided a ferry ticket from France to Guernsey and then a ticket from Guernsey to the UK, that was sufficent