I'm using S1 and Reaper, and have almost the same issue on both DAW.
In S1, although I check the box for Release audio device in background, there is no sound. Youtube and music players. The funny part is Youtube works fine on Opera browser, but not on Chrome.
Is there any solution?

Spec:
OS: Windows 10 64bit
CPU: i7 6700HQ
Ram: 16gb
Storage: 256gb SSD + 1TB SSD + 1TB HDD