InsertHandler not working

for (PsiPackage psiPackage: allPackages) {
    lookupElements.add(LookupElementBuilder.createWithIcon(psiPackage).withIcon(psiPackage.getIcon(1)).withInsertHandler(new InsertHandler<LookupElement>() {
        @Override
        public void handleInsert(InsertionContext context, LookupElement item) {
            System.out.println("test");
        }
    }));
}
LookupElement[] lookupArray = new LookupElement[0];
lookupArray = lookupElements.toArray(lookupArray);
LookupManager.getInstance(project).showLookup(editor, lookupArray);

Upon selecting the LookupElements, the handler doesn't fire and nothing shows up in console.