[yigi]

I have Mi Box 3 (MDZ-16-AB) which worked just fine until I accepted the Pie upgrade a few days ago.
The problem is that I see the Mi Box UI on the tv for half a second and than it disappears for few seconds. Sometimes if I let it be for a few minutes it will become stable but will happen again if power off and on again.
I tried factory reset, setting the screen resolution to auto, 720p, 1080p, 2160p and different 30,50,60 refresh rates, all end up with same behavior.
The Mi Box is connected  to LG SK10Y soundbar which is connected to ARC port (also tries other hdmi ports) of LG OLEDC6 tv.
The weird thing is that when the Mi Box is connected directly to TV it is working fine.
I tried replcaing hdmi cable same results.
The only thing changed was the upgrade of the Mi Box to pie. No new firmware for tv or soundbar.
Please anyone has a clue what can it be??

Thanks