Does CF7 integration still work?

Our CF7 form for RDW lookup for trucks used to work just fine: user puts in a license plate number and then the other truck data gets filled in automatically. But now every license plate number I put in just shows a yellow warning symbol next to the field and nothing happens. Something seems to be wrong, but the form is set up correctly as far as I can tell. There is no error message on the page, nor in the console log. Please see the link attached to see the form in action.

Has this integration been verified recently? I know CF7 gets updated regularly. Anyone else having problems? Here’s the code I’m using for the CF7 form (the HTML gets stripped by this WordPress forum, but the fields are present). Any help is appreciated.

Kenteken

[open_rdw kenteken id:kenteken]

Merk *

[text* merk id:merk]

Type *

[text* type id:type]

Handelsbenaming

[text handelsbenaming id:handelsbenaming]

Voertuigsoort

[text* voertuigsoort id:voertuigsoort "bedrijfsauto"]

Datum eerste toelating

[text* datum_eerste_toelating id:datum_eerste_toelating]

Vervaldatum APK

[text* vervaldatum_apk id:vervaldatum_apk]

Meer informatie

[textarea informatie id:informatie]

Geef hier bijzonderheden door zoals voertuigaanpassingen, schade of andere details. 

Foto's

[file foto1 filetypes:image/* limit:6mb]

[file foto2 filetypes:image/* limit:6mb]

[file foto3 filetypes:image/* limit:6mb]

Alleen afbeeldingen zijn toegestaan; maximale bestandsgrootte 6MB per foto.

Gegevens aanvrager

Voornaam *

[text* voornaam id:voornaam autocomplete:given-name]

Achternaam *

[text* achternaam id:achternaam autocomplete:family-name]

E-mailadres *

[email* email id:email autocomplete:email]

Telefoonnummer *

[tel* telefoon id:telefoon autocomplete:tel]

[submit class:button "Verzenden"]

The page I need help with: [log in to see the link]