MS Dynamics CRM and Adobe Sign (prefill fields missing)

Hey,

Here's my scenario: user loads template from file into MS Dynamics CRM. Template has Adobe syntax, defined here: https://helpx.adobe.com/sign/using/text-tag.html, for example prefill fields (you may find example in attachments).

Template works fine (fields work on CRM side), but when they're sent to Adobe, fields marked as 'prefill' which were for sure filled on CRM, are blank in Adobe.

We're using this add-on for integration: https://acrobat.adobe.com/lv/en/business/integrations/microsoft-dynamics-365.html

Is there a limitation to using 'prefill' fields with the add-on specified above or should they work just fine?

After calling API like this:

{host}/api/rest/v6/agreements/{agreementId}/formFields

fields definition is visible, but when calling:

{host}/api/rest/v6/agreements/{agreementId}/formData  

which should get their actual values, all the values which were not marked as 'prefill' are retrieved just fine, but all those which were marked as 'prefill' are empty / null.