I've been having the same sound problems on my Acer Nitro 50 since the last two Insider builds. I have been able to restore my sound by uninstalling my Realtek sound card in device manager, along with checking the box to remove the driver. After doing so, I will do a search for new hardware upon which the system will find and install the sound card, bringing my audio back. Unfortunately, shortly after this, the system will reinstall the driver and tell me to reboot to finish the installation. If I reboot, I lose all audio again. So what I am doing now is to leave my system running and if I do have to reboot for some reason, I will uninstall the audio card again and start over. While this is far from a permanent solution, it at least brings my audio back.
I have attempted to find updated drivers but have been unable to find any that are more recent than what is on my system. This is definitely a Windows problem and I hope they are looking for a solution, but really do not expect one. I expect to be having this bug until I inevitably purchase a new system in a year or so when the next Windows version comes out, or I format this one and start from scratch, which I really have no time or interest to do right now.