So that's the reason why V6S are out of stock everywhere. 🤔
Anyway, I got confirmed from my source that there isn't and won't be any firmware update for V6, that means the 1.0.0 is the one and only.
BUT apparently there is 2.0.0 for V6S actually.
I had exactly the same issue as you with some Switches and it was driving me nuts. Sometimes it was glitching, sometimes it was reporting random errors and when connected to PC it glitched everytime without hiccups. It turns out that as soon as the chip was pressed against the APU metal shield...