3.1.0 didn't work for me either but neither did 2.2.0, I had to revert to 2.1.0 to get it to "work".
"Work" is in quotes because:
TL;DR
While Go+ 2.1.0 appears to allow me to set ride parameters they are actually not working. They are saved and when I reload the ride parameters the last values I saved shows up but they don't actually make a difference. I was able to validate this with the
@Dado K1 flash tool (awesome tool).
The rest of the story:
I purchased the K1 flash tool from
@Dado and attempted to set the wheel size, circumference, speed, assist power levels, and startup angle. According to Go+ the only settings that were set were the wheel size and circumference. After emailing back and forth (thanks Dado for the excellent service) Dado suggested that I try setting the Eco assist level to 0 and see what happens.
First I tried setting it in Go+ which appeared to work and when I reloaded the app and restarted the display it showed 0, great works, right? Wrong, I still had assist, the same amount I had before I set it to 0.
Finally, I set Eco to 0 using the K1 flash tool and lo and behold there was no assist. I repeated this experiment 3 times and then set all of the assist levels to the values that I thought I had set using Go+ and wow, what a power difference. I had to tune them down a bit. I am confident that I will be riding in Tour mode rather than Sport mode for the majority of my rides.
I then proceeded to flash the 13A (43V) firmware (I had the 10A) and it went without a hitch. I am very pleased with my decision to purchase the K1 flash tool. I would have never known that Go+ is fake news.
Thanks
@Dado!
P.S. I suspect that Go+ is saving the values but to the wrong parameters so they are persisted across restarts but ignored by the firmware. They must have corrected this in the newer firmware versions. If you are in doubt I would suggest setting Eco power to 0 and see if assist is gone. If not, you might need Besst or a K1.