I would like to use an old Samsung Syncmaster T240HD (which has built-in speakers) monitor as an external display for my brand new Lenovo E15 laptop (including a fully updated 64 bit WIndows 10 Professional). If I connect this monitor to my laptop then my voice communication via Skype for Business disappears which means others can't hear me anymore. When I detach the Samsung display, the laptop microphone goes alive in the same moment.
What is interesing that connecting the Samsung device greys out the mic of laptop in the Skype for Business client, under Options / Audio Device, BUT the signal level of the mic stays visible and goes up and down during speech. Others cannot hear me though.