I have the same TV and the issue is not yet resolved. I have the latest firmware: Update says there is no newer firmware. I did a factory reset on my TV as suggested on multiple threads (losing all my settings - thanks for that). When I use my gmail account name and password, all I get is Login Failed. This used to work until about 4 months ago.
As a failsafe, just to check if it is not some obscure Google problem (linking Youtube and Google+, 2 Step verification etc) I created a fresh new Youtube account in Private mode in my browser. Using those credentials I tried logging into Youtube on the TV...Login Failed.
I have to admit. I am South African, but Sony SA has no MySony system. I emailed their support centre and first they said our version of Ofcom (ICASA) blocked it. After calling them out on the BS (and bitching about it on tech forums and threatening to claim my still valid warranty), they phoned me about a week later trying to help me over the phone. The guy clearly had no idea what he was advising me on. He suggested that I log into youtube on the TV's browser by giving me bogus URL's, then he suggested that I leave the fields open because my laptop on the same router is logged in etc, etc. Anyway he promised he will phone me back.
The reason for my little rant is this: Is it not maybe the firmware for my region that has not been updated yet? In case so, how do I trick my TV into downloading corrected firmware.
