Checkboxes on custom `WP_List_Table` also check select all

I ran into this same problem and did some digging. The jQuery selector to find the checkboxes includes an iedit class on the table <tr> elements. I assume this class is added via JavaScript on tables that have inline editing, but my <tr> elements had no classes as I’m not using inline editing.

I was able to solve the issue by adding this method to my table class. You may need to do some minor tweaking to get the iedit class there if you already have a class attribute on your rows.

public function single_row( $item ) {
    ob_start();
    parent::single_row( $item );
    $output = ob_get_clean();
    echo str_replace( '<tr>', '<tr class="iedit">', $output );
}

And here’s the source JavaScript with the issue: https://github.com/WordPress/wordpress-develop/blob/b4889e474c77ba4ed7a492441fd948eb124a3e77/src/js/_enqueues/admin/common.js#L1172