I may be wrong but this could be due to an outdated driver. Make sure that your mic has the latest driver installed just like your Windows has the latest updates. If this does not solve the issue, it is still possible that it is a driver issue but the new driver could be clashing with Windows or the games. Then, I would try to go back and install an older mic driver that used to work properly.
HTC U12 Plus review: Hands-on