I am getting "Invalid date" for adding a task that's "Every Saturday." I tested things like "Every Monday" and they work, so it seems like Saturday is not working.
And this is odd... it seems true for just one task. I'll experiment further.
Strange, now it works. I consistently tried for 5 minutes going back and forth between days and "Saturday" was failing. It's happy again.
There was a bug breaking multiple recurring date formats, it's been already fixed yesterday, but your browser might have still used the cached unfixed version. Please log out and back into your account to make sure the latest version gets loaded (even though it seems to be already as the date works for you now).
Thanks! Glad to know I hadn't gone crazy or forgotten how to properly spell "Saturday." :)