For the last week or so some Strava activities haven’t been delivered to Intervals.icu. If this happens use the “Download old data” button in the Strava box in /settings to retrieve the missed activities.
Do not do “Revoke Access”! Intervals.icu is required to delete all of your Strava activities if you disconnect. There is a delay but it is better to not risk it. Use the “Update Permissions” button if you think your Strava account is not properly connected to Intervals.icu. Make sure you are logged in to the correct Strava account in the browser before doing “Update Permissions”.