I wasn't going to post this but definitely a weird thing..
New gym uses the commercial grade treadmills... And they are set to miles as default
I use my stryd distance in km's and garmin fenix 5+ km's, and communicate across them ant+, and to hrm-run v2 belt.
Anyway if I don't change the treadmill to kms, and start a run, whatever the precor is outputting seems to confuse either the watch ajd/or the stryd, as I can see speed go from say 6 to 9 and back every 3 or so seconds. Simple fix is set treadmill to miles.
As said weird, never had the issue on my own personal treadmill.
Using latest beta minus 1.
:)