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.
{
    if (!walletFrame) return;
    walletFrame->setCurrentWallet(wallet_model);
    for (int index = 0; index < m_wallet_selector->count(); ++index) {
        if (m_wallet_selector->itemData(index).value<WalletModel*>() == wallet_model) {
            m_wallet_selector->setCurrentIndex(index);
            break;
        }
    }
    updateWindowTitle();
}
void BitcoinGUI::setCurrentWalletBySelectorIndex(int index)
{
    WalletModel* wallet_model = m_wallet_selector->itemData(index).value<WalletModel*>();
    if (wallet_model) setCurrentWallet(wallet_model);
}
void BitcoinGUI::removeAllWallets()
{
    if(!walletFrame)
        return;
    setWalletActionsEnabled(false);
    walletFrame->removeAllWallets();
}
#endif 
void BitcoinGUI::setWalletActionsEnabled(bool enabled)