I have made a custom label for product package. It works the way it is supposed to on my localhost and on a test server on odoo.sh. However on our client's server it prints in only one column instead of two:
<?xml version="1.0"?>
<t t-name="custom_package_barcode.report_package">
<t t-call="web.html_container">
<t t-call="web.basic_layout">
<t t-foreach="docs" t-as="o">
<t call="web.external_layout">
<div class="page">
<div class="row mt32 mb32" id="package_info">
<div class="col-auto mv-200 mb-2">
<div class="col-12 text-center" style="padding-top:200px;">
<p t-field="o.product_id.name" style="font-size:12px;align-self:end;justify-self:end;">
</p>
</div>
</div>
<div class="row mt32 mb32" id="package_info">
</div>
<div class="col-auto mv-200 mb-2">
<div class="col-12 text-center">
<img t-att-src="'/report/barcode/?type=%s&value=%s&width=%s&height=%s' % ('Code128', o.name, 450, 150)" style="width:300;height:100" alt="Barcode"/>
<p t-field="o.barcode" style="font-size:12px;"/>
<strong>QUANTIDADE</strong>
<p t-field="o.qty" style="font-size:12px;">
</p>
</div>
</div>
</div>
</div>
</t>
</t>
</t>
</t>
</t>