ODK Web Forms not working

I wanted to try the new ODK Web Forms by adding a new submission to one of my working forms (also Enketo working) and I get the message "An error occurred while loading this form" and the technical error details "AxiosError: Request failed with status code 404
at Ib (https://odk.myserver.xxx/assets/index-r8rPv4_m.js:49:1083)
at XMLHttpRequest.x (https://odk.myserver.xxx/assets/index-r8rPv4_m.js:49:5718)
at ys.request (https://odk.myserver.xxx/assets/index-r8rPv4_m.js:51:2068)
at async ExternalSecondaryInstanceResource.load (https://odk.myserver.xxx/assets/web-form-renderer-Db6WVC0j.js:284:7193)
at async https://odk.myserver.xxx/assets/web-form-renderer-Db6WVC0j.js:284:12393
at async Promise.all (index 0)
at async SecondaryInstancesDefinition.load (https://odk.myserver.xxx/assets/web-form-renderer-Db6WVC0j.js:284:12049)
at async loadFormResult (https://odk.myserver.xxx/assets/web-form-renderer-Db6WVC0j.js:286:75883)
at async loadFormState (https://odk.myserver.xxx/assets/web-form-renderer-Db6WVC0j.js:286:78006)
at async https://odk.myserver.xxx/assets/web-form-renderer-Db6WVC0j.js:3439:55197

Do I need to change some other settings?
Thanks