My 945 used to snap to track very effectively in track run mode.
About 6-8 weeks ago it stopped doing so.
Now I have a new FR255. It also fails to snap to track. I have tried calibrating by doing 4 laps in lane 1 etc, but no luck.
Track is conventional oval with single radius. And, as I said, it used to work completely fine.
Since this issue bridges two different watches I suspect it is a firmware issue.