Data type Date not sorting on a line chart

I'm trying to display some data on a line chart. Specifically, I want them to be split by week. I have a column called EventDate that contains DateTime values. To classify them by week, I created a custom column that performs the following:

Week =
    if Date.IsInCurrentWeek([EventDate]) then
        null
    else
        Date.StartOfWeek([EventDate])

I have a page-level filter that removes anything that is null, so the conditional is there so that it doesn't display data for the current week until it's over.

When I try to display the data over a line graph, I get the following:

As can be seen from the screenshot, the date sorting is off, as it appears to be sorting it as if the labels were strings. If I click on the ... on the top right and click on Sort By Week, the problem persists. Why is this? How can I fix it? Looking at the query itself, the Week column is of type Date, not Text.

Thank you!