When I start up the Alpe for the first 3 or 4 sections it shows my best section time as something ridiculous like 3 seconds. It seems to be using my downhill times as my best for the section. Once I get to maybe section 4 it starts reporting my accurate best times for going uphill.
Same for me.
Yes, this has been a bug for a while. See Alpe Du Zwift Sectors 1, 2 and 3 Show Incorrect PRs