InfoPath Dev

I have a fairly large form set-up with multiple people fields. When I launch and fill-out the form from the SharePoint site, the validate and search buttons for the people fields work without issue. I have an individual helping me test out the form and they have the same privileges on the SharePoint site as I and yet when they try to use the buttons on any people field, they do not function. We are using the info path form application and not the browser based-form. Any suggestions? I've done a number of searches online and nothing seemed to solve my issue. One involved changing a site web config but I do not have access and it would likely be a challenge to get the values changed. Unfortunately I cannot even add custom code. Thank you in advance for any help!

Ick. https://docs.microsoft.com/en-us/sharepoint/troubleshoot/sharing-and-permissions/picker-field-embedded-does-not-show-add-people has some suggestions - you may want to install something like Fiddler on the machine for the user experiencing the issue so you can try to get more info about what is happening when they try to pick a person.... you'd at least then know if this was something your IT / SharePoint admin group was going to have to address....

Thank you Hilary! This makes sense, I've got an idea from this. Will report back soon.