Search conditions do not work in i4. In objectUI of workflows that you execute in I4, GN4 browser and GN4 clients, use the template command instead, as shown below (text in red):

  <attribute name="sourceRef">
    <ui mode="Normal" initMode="LastUsedNone">
        <searchConditions xmlns="http://www.teradp.com/schemas/GN4/1/XmlSchemaExt.xsd">
            <SearchNode
            xmlns="http://www.teradp.com/schemas/GN4/1/SearchConditions.xsd"
            xsi:type="SearchConditionList"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
            <List Op="Starting" Path="[source.name]" FromValue="Redazione "/>
            </SearchNode>
        </searchConditions>
        <template
             xmlns="http://www.teradp.com/schemas/GN4/1/XmlSchemaExt.xsd"
             kind="DropDown" sorted="true" filter="starts-with(@name, 'Redazione ')">
        </template>
    </ui>
  </attribute>