I used the ‘link to strava account’ link under profile settings to link a zwiftpower account to a strava account. The redirect URI is incorrect as it points to "www-dot-www-dot-zwiftpower-dot-com (sorry about the ‘-dot-’ but this forum won’t let me post the actual URL). Rather than “www-dot-zwiftpower-dot-com”. So it gives an error in the browser because it cannot find that bad URL. However, Strava does return a correct code and so a simple manual edit of the return URL to remove the extra “www.” solves the issue easily…but many won’t know to do this so you’ll want to fix it in your Strava API application - Authorization Callback Domain URL setting.