Microphone is not working when loudspeaker is on

Hi! I have a problem with my m4. The mic seems to turn off when i switch to loudspeaker during a call or if i start a fb messenger call with camera on. However the mic works fine with normal calls, i can record, use google speech etc. Mic test succeeded. Safe mode on and the same thing happens. I have put newest rom for central europe 26.1.A.2.147, wiped all possible data via flashtool and even on clean phone without any apps the problem still exists. I did not change any settings or so. It is just the mic not working when i wany to use loudspeaker ( the onr on the bottom of the phone). I also had issues with lower volume levels than in other m4, but here the rom update might help - i will see in fee days as i did rom update today. Do You have any idea what is wrong? The phone never had contact with water etc.

Loudspeaker not working

I recently replaced my charging port as it stopped charging recently without bending the charger when laying to make it charge.. When i turn on the phone the loudspeaker no longer works, and i cant see why it shouldnt. Yesterday i recieved a new speaker in the mail, in case it somehow got damaged in the first replacement, tried that one, same issue..
I tried cleaning the contact points on the board the speaker has its contact on, but same result. Is there a service code or something i could try to enter, or any suggestions what other things to try?
All ebay purchases and the phone itself should be G900F model. The front facing speaker works
Running latest nightly CM12