WalletConnect Session Handling (with Metamsk) - No Metamask Confirm Dialog after first transaction

I have a web app using Wallet to send ERC20 transactions (contract interactions -> transfer). I am using Metamask (mainnet) to interact with the web app. For the login (connect) I get the confirm dialog in Metamask, so do I for the first transaction. However, from the second transaction on, I don't get the confirm dialog. Does anyone know what the problem could be?

I have a web app using Wallet to send ERC20 transactions (contract interactions -> transfer). I am using Metamask (mainnet) to interact with the web app. For the login (connect) I get the confirm dialog in Metamask, so do I for the first transaction. However, from the second transaction on, I don't get the confirm dialog. Does anyone know what the problem could be?

// SESSION INIT
const providerOptions = {
  walletconnect: {
    package: WalletConnectProvider,
    options: {
      infuraId: INFURA_ID,
    }
  },
};

web3Modal = new Web3Modal({
  cacheProvider: true, // optional
  providerOptions, // required
  disableInjectedProvider: false, // optional. For MetaMask / Brave / Opera.
});

console.log("Web3Modal instance is", web3Modal);

try {
  provider = await web3Modal.connect();
} catch(e) {
  console.log("Could not get a wallet connection", e);
  return;
}


//SEND TRANSACTION
async function transferMoney(toAccountId, amount, tokenContract) {
  var data = tokenContract.methods.transferByAccountId(toAccountId, amount).encodeABI()
  console.log(data)
  var gasPrice = await web3.eth.getGasPrice()
  const tx = {
    from: selectedAccount,
    to: tokenContract.options.address,
    gas: TRANSFER_GAS_ESTIMATION,
    gasPrice: gasPrice,
    data: data,
  };
  try {
    console.log(tx)
    var txHash = await provider.connector.sendTransaction(tx)
    console.log(txHash)
  } catch (err) {
    console.log(err.message);
  }
}

// DISCONNECT SESSION
async function onDisconnect() {
  console.log("Killing the wallet connection", provider);
  if(provider.close) {
    await provider.close();

    await web3Modal.clearCachedProvider();
    provider = null;
  }
  selectedAccount = null;
  location.href = 'login.html'
}