Using master (98958c81f5065a5de13699d46995d278ecb6709e) with Qt `5.12.3` (also tested with depends) with multiple wallets available. None are shown in the `Open Wallet ->` menu in the gui. The wallets can be loaded from the console, bitcoin-cli etc.
{
#ifdef Q_OS_MAC
    
    appMenuBar = new QMenuBar();
#else
    
    appMenuBar = menuBar();
#endif
    
    QMenu *file = appMenuBar->addMenu(tr("&File"));
    if(walletFrame)
    {
        file->addAction(m_open_wallet_action);
        file->addAction(m_close_wallet_action);
        file->addSeparator();
        file->addAction(openAction);
        file->addAction(backupWalletAction);
        file->addAction(signMessageAction);
        file->addAction(verifyMessageAction);
        file->addSeparator();
    }
    file->addAction(quitAction);
    QMenu *settings = appMenuBar->addMenu(tr("&Settings"));
    if(walletFrame)
    {
        settings->addAction(encryptWalletAction);