Something I learned:

If you click a link to something on the site (like you click the link to the activity page), and it signs you out as soon as you do, refresh the page and you’ll be signed back in most of the time. Don’t log back in if it signs you out on its own when you click on for example, the activity page, or it’ll take you to the dashboard for some reason

Don’t know if this is a safaria issue or a site issue