Seems that is a common issue with vive pro, headphones will start to fail eventually with use, good thing is that those can be replaced easily. A more permanent solution will be to use the Vive DAS (Deluxe Audio Strap) and replace all the back part of the headset, DAS has appeared to be way more sturdy and headphones can be connected to vive pro with USB C to headjack adaptor. You will also need a headset mount adaptor, this is available to 3D print for free on thingiverse