Stereo+ dont work in landscape mode after screen is switched off

[Igor Nikolic]

Hello. I have Huawei Mate 9. After Oreo upgrading, when listen music in landscape mode stereo works fine but if turn off the screen sound become like in portrait mode - mono. On previous Nougat version everything was working fine. Any ideas? Thanx.

 

[GentleMuser]

I can confirm that mine does this also.
sound still comes out of ear speaker, but volume and tone are much weaker....