InfoPath / SharePoint 2010 issue with people picker fields not showing

Hi all -
I'm new to this, so I have no idea if the development forum is the correct place to post an InfoPath / SharePoint customization question, but I'm hoping somebody may be able to point me in the right direction.

Background:

I have a SharePoint 2010 list, on which I have used the 'Customize form' feature to modify the default form through InfoPath.

I then have an InfoPath form web part on a page, where I want the data displayed in the form to be based on an ID parameter passed via the page URL. I have achieved this using a simple query string (URL) web part on the same page. This works by:
- Through the Manage Web Part Connections in SharePoint Designer, set the value of a new hidden field in the form which I've called 'ID_LookupFromURL'.
- In the form template, I have a rule that runs when the 'ID_LookupFromURL' field changes, it sets the ID query field to the same value, then looks up the data from the main data connection, which is then displayed on the form.

Issue:

This entire process is working almost perfectly at the moment, but the only problem is that any people picker fields on the form are hidden when the form first loads. This does not happen if I load the form normally without passing a URL parameter. It seems there is an extra delay with processing the people picker values, and when I use this extra step in pre-loading the form through the URL parameter, it interferes with the process which shows the people pickers.

When filling out the form, if I change any field that requires a lookup to another data connection (anything that requires the form to send information back to the server or lookup information from the server), only then will the people picker field show. It is as if it requires an extra connection back to the server for the people picker fields to render.

Any ideas on what may be causing this issue?