Add From Contacts NOT Working... Please help!

I’m new to this forum, but desperately need some of your expertise to help me fix the current situation.

I’m a front end developer, but hired a couple of guys to do the backend for the app. One of the features involves “ADD FROM CONTACTS”. When you click on the input box to add from contacts it should auto populate, but it does nothing. It IS working on the developers end, but NOT working for me or the client. The input field “should” populate ONLY the contacts that have an email address… nothing shows up. However, when I get to the screen it does ask me to access my contacts on my phone.

I hope I’m explaining this correctly. If anyone can give me any kind of advise or help it would be very appreciated. The backend developer seems to not be able to get this working properly. This is the only thing within the app thats lacking…

Thank you so much