Steps to reproduce the issue

    <field name="myfield1" default="1" type="list" label="Testfield 1" layout="joomla.form.field.list-fancy-select">
        <option value="1">Value1</option>
        <option value="2">Value2</option>
        <option value="3">Value3</option>
    </field>
    <field name="myfield2" type="number" default="0" label="Testfield 2" filter="unset" min="0" showon="myfield1:2" />

Expected result

myfield2 should display when Value2 is selected.

Actual result

showon is not working.

System information (as much as possible)

Joomla 4.0.2 (works in J3)

Additional comments

Works when field is a non fancy non multiselect list.