I've had similar issues but it's not consistent as your seems. These devices seem to have a lot of sleep/wake up bugs. I have have a 5i5RYK and the sound gets muted once in a while when waking from sleep and won't "unmute" until a reboot. I'm running Windows 10 64bit. I'm passing audio through the mini DP to the monitor which has an 3.5 mm jack.
Intel is aware of the issue related with Windows 10 and the Intel® graphics, our engineering department is working on a new graphics driver. You can post your issue and see more information here: