I had/have the same issue before/after BT Stage 1 on my 2020 K67 with full Akra. I posted here but only suggestion was to be firmer and press harder when down shifting. That helped, but I started to experiment and I found that 40-45 mph range is the sweet spot for 2nd to 1st downshifts. Any speed below 40 mph is prone to false neutrals on my bike when using quick-shifter. I adjusted my riding style and that seems to help 99% of the time. I still hit false neutral from time to time, but usually when I am lazy. I just use clutch when I need to shift at lower speed. Hope that helps.