After using live segments on my Fenix 5 for a year, I tried live segments on my new Fenix 5 plus yesterday. What a mess! On the tested segment, my PR is 17 minutes, and the CR is 13 minutes (i.e. unreachable for me). But since I can't choose to race PR only, the watch kept jumping between CR and PR as target every few seconds. It was so annoying, that I don't think I will be using Strava Live segments until the option to choose PR as target is back.
Nevermind, I just found out how to turn off "Auto Effort"... :o