I am based in the UK so our date fields are set to be in the format dd/mm/yyyy.
For the database i am building we update it from an onsite third party specialist application once a day and it appears that dates such as 1/12/2021 i.e missing the leading zero are just ignored when using the periodic import from URL.
I am going to look in to getting a leading zero added if i can but at this moment in time i am not sure what the on site third party app is capable of producing.
cheers
Matt