The issue:
When a URL like the one below is used in emails and click tracking is turned on, the id and password parameters are lost.
https://ask19.synovate.net/demo.dll?project=J2M8601&id=10003876&password=314870

The cause:
The parameters are lost when this type of URL is used as a merge field. If this URL were to be explicitly included in the email, it would work fine. URLs that are explicitly included in emails that contain URL parameters have the ? and & replaced by the system with %3F and %26, respectively. However, if the URL is part of a merge field, these replacements do not take place.

As a click-tracked link from a merge field, this will work:
https://ask19.synovate.net/demo.dll%3Fproject=J2M8601%26id=10003876%26password=314870

This does not work:
https://ask19.synovate.net/demo.dll?project=J2M8601&id=10003876&password=314870
(They will both work as presented above, but as part of a click-tracked link, only the first one works.)

Solution:
So, in order to provide click-track reporting in BNContact and to preserve the entire URL, the survey URLs must be modified to replace the ? and & with %3F and %26, respectively. Again, this is only an issue when a URL of this type (with URL parameters) is included as part of a merge field, for example, {{{url}}}.