Topic: Switch & 5.1 speakers - no subwoofer channel

Hello,
recently I have noticed strange behaviour of my Nintendo Switch. When I play in dock mode and my dock is connected to av receiver using HDMI, there is no subwoofer channel on my 5.1 system. I have checked everything and all is connected properly. AV receiver is set in direct mode which means that it should output exactly what Switch puts on input. My AV receiver is capable of handling LPCM 5.1 signal (Onkyo TX-NR686). When I play test sounds in console's menu after selecting "surround" all channels work, but in games there is no subwoofer. I started to dig in the internet and found this: https://en-americas-support.nintendo.com/app/social/questions... . I also asked my friends with similar setup (5.1 speakers, av receiver, Switch) and they don't have subwoofer channel in games as well. This is clearly some major bug in Switch firmware which was introduced at some point since I am sure it used to work once.