Update in Vivo situation:

[RavenSirius]

Just to let you know, after more than 60 emails back and forth with Vivo Support, they have fixed the sound problem.

If you have a Vivo phone with build number:

PD2147GF_EX_A_38.12.1

or better, then the sound will work properly...or should.

[Travis | Support Mgr.]

Nice, thanks for the update!

[WarriorSeven]

It's impressive that you actually got the OEM to not only address your emails but to also solve the problem.