I have serious issue with my phone. Sometimes it suddenly muted by itself and I can't set the volume up, only rebooting is the solution. Not every sounds are muted: only the ringtone, alarm, notification sounds but screen lock/unlock sound is works.

Hi there!
Unfortunately your issue is definitely uncommon and not reproducible.
Considering that, I suggest you to update your device to the latest firmware (20180124) and after that perform a factory reset.

If this can't solve your issue, it may be related to an hardware fault. In this case i reccomend you to contact your seller for a replacement under warranty.

There is the latest firmware on the phone (20180124) and I made a factory reset but later than I installed the update. After updating (but before the factory reset) the problem occurred more often. The phone is never totally mute just some kind of sounds are missing (but vibrating function always works)
My previous phone was a BV6000 with the same problem... I need to look for another brand I think.

Rexi wrote:

There is the latest firmware on the phone (20180124) and I made a factory reset but later than I installed the update. After updating (but before the factory reset) the problem occurred more often. The phone is never totally mute just some kind of sounds are missing (but vibrating function always works)
My previous phone was a BV6000 with the same problem... I need to look for another brand I think.

Sorry but i can't understand: did you perform a factory reset after the update?

blackview_admin wrote:

Rexi wrote:

There is the latest firmware on the phone (20180124) and I made a factory reset but later than I installed the update. After updating (but before the factory reset) the problem occurred more often. The phone is never totally mute just some kind of sounds are missing (but vibrating function always works)
My previous phone was a BV6000 with the same problem... I need to look for another brand I think.

Sorry but i can't understand: did you perform a factory reset after the update?

Yes I did, but not right after installing the firmware update just a few weeks later. Anyway this method is annoying a little bit... Why can't do the firmware update via OTA? And without spend time to save and restore my personal data?

Rexi wrote:

blackview_admin wrote:

Rexi wrote:

There is the latest firmware on the phone (20180124) and I made a factory reset but later than I installed the update. After updating (but before the factory reset) the problem occurred more often. The phone is never totally mute just some kind of sounds are missing (but vibrating function always works)
My previous phone was a BV6000 with the same problem... I need to look for another brand I think.

Sorry but i can't understand: did you perform a factory reset after the update?

Yes I did, but not right after installing the firmware update just a few weeks later. Anyway this method is annoying a little bit... Why can't do the firmware update via OTA? And without spend time to save and restore my personal data?

OTA updates may be tricky, they don't reach every user and sometimes may behave in an odd way, expecially if not followed by a factory reset.