I’m also having a problem with inaccurate calibration of my SNAP 17. I only use the Wahoo App for spindown.
I thought the issue is caused by a longer spindown time due to a different trainer tire. Wahoo tells me that this isn’t a problem. I would love to see some numbers to back that up. I’m hoping that someone with a SNAP and a power meter on their bike will run an experiment and post the results.