I have added lookup method on StringEdit(InvoiceIdMultiselect) formcontrol as follows:
public void lookup()
{
Query query = new Query();
QueryBuildDataSource queryBuildDataSource;
queryBuildDataSource = query.addDataSource(tableNum(VendInvoiceJour));
queryBuildDataSource.addRange(fieldNum(VendInvoiceJour,PurchId)).value(PurchId.valueStr());
queryBuildDataSource.addSelectionField(fieldNum(VendInvoiceJour, InvoiceId));
queryBuildDataSource.addSelectionField(fieldNum(VendInvoiceJour, PurchId));
msCtrl = SysLookupMultiSelectCtrl::constructWithQuery(this.formRun(), InvoiceIdMultiselect, query);
//super();
}
On testing, when I am changing PO, lookup values are not updating,

But when I am closing the form and reopening, it updates the data.
Any solution?