I have the same problem with my Samsung s8 when I put my phone on vibrate and take it back off , my notifications get muted. I always have to put it back on and it's frustrating.
I have a Samsung S8 and every time I put my volume on vibrate and put it back on sound my notifications get muted. The notifications volume doesn't go back to Sound. This is obviously some sort of bug, does anyone have a fix for this?