Thank you for the file.
The <DATE> tag in your file is
<DATE>16-08-2018</DATE>
while in the file generated on my PC is
<DATE>16/08/2018</DATE>
EBU only accepts the 16/08/2018 format otherwise it asks you to enter the date manually.
The reason that your date is formatted in a different way might be that your PC locale is set to something different to mine, which is
Time zone
(UTC+00:00) Dublin, Edinburgh, Lisbon, London
Formats...
Short date: 16/08/2018 etc.
At the moment I cannot find a way to force the correct format - googled it a bit and this didn't help.
Which locale do you use?