New to strava, but it didn't sync the last month of activities like support page said.

Hi everyone, I just got Strava and did some research on connecting Garmin connect to Strava. This link said that after a new activity is completed, it would automatically grab the last 30 days of activities from Garmin. I connected the accounts after my run today, but only today's run is showing on Strava, and none of the ones from the past 30 days are there.

Is there a reason they aren't showing up? Just kinda confused on how the process works. Thanks