Hello - I posted this issue to Technet last week but it did not get any traction there. It may be easier to read through in the Technet article here (screenshots): https://social.technet.microsoft.com/Forums/office/en-US/9f45c2e7-f745-45c0-92ac-a1295bfcaa17/infopath-2010-people-picker-browse-not-working-in-sharepoint-2016?forum=SP2016#9f45c2e7-f745-45c0-92ac-a1295bfcaa17
We recently did the double hop migration from SP 2010 > SP 2013 > SP 2016 and noticed that in our InfoPath 2010 browser enabled forms, all the people picker fields do not populate anything in the browse tool. We can still use display name, first initial last name, and email address to resolve those fields with the check names button, but the browse feature does not work.
Note: SharePoint people picker fields work fine. The issue is only with InfoPath 2010 > Browsing all users.
I shouldn't say the browse feature doesn't work entirely; it does render results when I set the SharePoint server URL and set the Choose from: field in the InfoPath people picker field properties to a SharePoint group.
I did try changing the web.config line fix that some have mentioned trying with similar issues, but that didn't work in our environment.
https://social.msdn.microsoft.com/Forums/sharepoint/en-US/d6fa5812-64e0-4d80-94b0-0577ba43ce59/sharepoint-2013-infopath-2010-people-picker-does-not-works-when-opens-in-client-application-but?forum=sharepointcustomization
If you have any ideas for further troubleshooting or any suggestions at all, please let me know. Thanks!