FIX VOLUME SLIDER BAG - MIUI 11 - MIUI 10 FIX

Link for full guide: droidapps.cf/e...
How to fix a freezing volume slider after changing it.
When the smartphone volume is increased using the side buttons, as usual, the volume control appeared on the right side of the screen. It should disappear almost immediately. But in this case, this did not happen. The controller continued to hang on the screen over all the windows.
You need to find a service that uses the volume or controls the sound and turn it off. If you can detect this application, you need to restart the phone and the slider will again go away as before.