Audio issue during a meeting

Recently, I have been facing an issue with my audio during a meeting with my mentor. He cannot hear me, but the audio input of my microphone during the meeting is fine. I can see the input level increase when I speak. What I've done so far is:

1) Checked if I selected the correct microphone channel. 

2) Tried my pc, headset inputs and the issue still persists.

3) I've used also my iphone microphone and did not work. 

4) I've joined the meeting from my iphone only instead desktop that I usually do and still not working. 

5) Checked his settings also and they were ok!

* Bear in mind that I have a connected audio interface (Focusrite) but it worked fine in the past!

I cannot identify what is causing this issue! Please help!