Odoo v.19 not loading CSS file from assets

I read that from Odoo v.17 onwards, CSS files should be listed under the assets section of the manifest file, like so:

    'assets': {
        'web.assets_backend': [
            'mydashboard/static/src/css/dashboard.css',
            'mydashboard/static/src/js/dashboard.js',            
        ],
    },

But for some reason, the CSS is not loading or being applied to the templates.

The CSS works if it is included in a style block within the template itself, like so (truncated version):

<?xml version="1.0" encoding="UTF-8"?>
<odoo>

  <template id="my_dashboard_meta" inherit_id="web.layout">
    <xpath expr="//head" position="inside">
      <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    </xpath>
  </template>

  <template id="custom_dashboard" name="My Dashboard">
    <t t-call="web.layout">

      <style>
        @font-face {
          font-family: LCD;
          src: url("/my_dashboard/static/src/fonts/lcd-regular-webfont.ttf");
        }

        html {
          font-family: LCD, Times, serif;
        }

        .kanban-card {
          border: 1px solid #ddd;
          border-radius: 8px;
          overflow: hidden;
          background: #fff;
          display: flex;
          flex-direction: column;
          align-items: center;
          text-align: center;
          margin-bottom: 30px;
        }

        .kanban-card img {
          width: 200px;
          height: 150px;
          object-fit: cover;
          flex-shrink: 0;
        }

        @media (max-width: 1200px) {
          html {
            overflow-y: scroll;
          }
        }

        @media (max-width: 600px) {
          html {
            overflow-y: scroll;
          }
          .kanban-card img {
            width: 240px;
            height: 180px;
          }
        }
      </style>


      <div>
        <t t-set="action_quotations" t-value="request.env.ref('sale.action_quotations', False)" />
        <t t-if="action_quotations">
          <div class="kanban-card kanban-4">
            <a t-att-href="'/web#action=%s' % action_quotations.id">
              <img src="/my_dashboard/static/src/images/sales_icon.png"
                alt="Incoming Inventory" />
              <div class="content">
                <p>Pending Sales</p>
              </div>
            </a>
          </div>
        </t>
      </div>
      
    </t>
  </template>

</odoo>

Any idea why?