Missing media sound adjust bar

[Drive7726]

When playing music by application, usually media sound can adjust by use sound adjust button then in notification bar appear media sound. But now it's missing.
I cannot adjust music until restart phone

[MarlonUk1]

are you using the built in music player?

how about when you adjust the volume using the volume keys? does it show the volume bar?

can you try to see if this happens when you are on safe mode?