How can I fix Voxer app Speakerphone mode?

I love the Voxer app as I find it is a more efficient way of communicating. A few months ago, however, and for no apparent reason the Voxer app stopped functioning properly. I normally use it in Speakerphone mode as if it is a walkie-talkie but suddenly the app stopped allowing my voice to be recorded while in speakerphone mode. I can receive audio messages from others while in speakerphone mode and they will play through the speaker but my voice will not record and when the other party receives the message that I have sent it does not have any audio contained in it. The app will still function normally in Headset mode but I do not prefer this mode. I contacted Voxer directly and have been working with them to resolve this issue for the past few months. We literally have tried every possible fix besides replacing my phone. We have, enabled and disabled the mic in the settings, we have deleted and reinsalled the app, we have sent debugging details from each message recorded, we have upgraded the app to the pro version, we have experimented with a beta version that I was allowed to test on my phone, we have also restored my phone from a backup and as a new phone after erasing the entire phone. Nothing has fixed this issue and yet when testing out other apps that use the mic in the same manner that Voxer does while in speakerphone mode all the other apps function as they are supposed to, this includes the stock apple Voice Memo app. Voxer has no other known issues of this type from other users which leads me to believe that somehow my phone's hardware deciced to not allow Voxer to function in Speakerphone mode. Does anyone at Apple or that is a developer know what could have caused this or how it can be fixed? Is this an issue that I could get my phone replaced because of? Thanks for any suggestions as they are very welcome.