Switched to a Mi 8 from a broken iPhone. Upgraded to MIUI 10.3.4 this weekend and after installing a bunch of apps got a phone call and realised my ear speaker isn't working. Headphones work fine (both calls and music), the big speaker (at bottom of phone) works too (both calls and music). I've done the test using *#*#6484#*#* and it fails for "8.Receiver", i.e. I do not hear any sounds from the ear speaker. I've googled for solutions and followed multiple advices with to result.
What I've done so far:
1) Rebooted multiple times - no fix
2) Turned on and off - no fix
3) Listen to songs with headphones and w/o for 5+ mins - no fix
4) Plug in and uplug headphones via the 3.5mm jack during a phone call multiple times - no fix

a) I could try factory reset the phone (which should also take me to MIUI 9.x.x) and see if that helps.
b) In a similar thread about sound https://c.mi.com/thread-2119722-1-0.html someone from the device team suggests to "do clean flash via mi flash tool.." however when I check this page https://www.xiaomiflash.com/ Mi 8 is not listed as a supported device
c) Contact gearbest.com where I purchased the phone and inquire about warranty. I live in London and contacted the Xiaomi UK store but they say they don't cover phones sold via Gearbest

Kind regards,