RichardB-holland

Yes found it!!
This is the error I get (read 'ssn' where it says 'bsn' due to my translation for asking this question in the forum).
Fatal error: Uncaught mysqli_sql_exception: Data too long for column 'bsn' at row 1 in /var/www/html/Requests/Scripts/wsrequest-person.php:143 Stack trace: #0 /var/www/html/Requests/Scripts/wsrequest-person.php(143): mysqli_query(Object(mysqli), 'INSERT INTO per...') #1 {main} thrown in /var/www/html/Requests/Scripts/wsrequest-person.php on line 143
Silly me, I used the dutch translation for 'anonymized' which is 'geanonimiseerd' and this exeeds the maximum length of 11 characters for the column.
I now found out that in the Xamp stack the same script did not throw in any errors but the word 'geanonimiseerd' was stripped to 'geanonimise' (which is 11 characters long). In the Lamp stack the row was completely ignored. Maybe this has something to do with the PHP version.
Anyway, it works in the production environment now. Thank you so much for pointing me in the right direction 🎉