Hi Jenni,
> As Philipp said, "Subscription center functionality" is not supported by Captured external form,
you could switch to "Embbed marketing form" if you had requirement for subscription management.
https://docs.microsoft.com/en-us/dynamics365/marketing/embed-forms
> For your capture form itself, have you checked following records?
* submission value(enable "Store form submission" field in Summary tab to Yes)
* submission in insights data
What's more, what's version of your form-loader.js? Mine is 1.59.1039.0(it was created by system automatically.) and the feature works for me.
https://mktdplp102cdn.azureedge.net/public/latest/js/form-loader.js?v=1.59.1039.0
> There are following methods to insert data into Dynamics without authorization from client side.
* Marketing form.(Landing page type)
* Entity form.(disable Entity permission of the form, and Portal integration is required.)
* Power Automate(Philipp suggested), link your Dynamics environment with other platform by connectors.
> In addition, how did you build your captured form?
In this previous thread, the user built his captured form by a plugin in Wordpress,
and the plugin added extra attributes "action=..." and "method=POST", normally these attributes are used to request our own web service on our own server,
which might causes collision with form-loader submission detecting behavior, you could also check this.
Regards,
Clofly