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.
{
    assert(!m_wallet_controller);
    assert(wallet_controller);
    m_wallet_controller = wallet_controller;
    m_open_wallet_action->setEnabled(true);
    m_open_wallet_action->setMenu(new QMenu(this));
    connect(wallet_controller, &WalletController::walletAdded, this, &BitcoinGUI::addWallet);
    connect(wallet_controller, &WalletController::walletRemoved, this, &BitcoinGUI::removeWallet);
    for (WalletModel* wallet_model : m_wallet_controller->getWallets()) {
        addWallet(wallet_model);
    }
}
void BitcoinGUI::addWallet(WalletModel* walletModel)