QR API not working: Cannot construct STArray from value given

Hello, I was getting custom qr-code (code shared below) depending upon the amount and avax_address but now I am getting the following errors:

library version: "xumm-sdk": "^1.8.4"

Internal error code: 603
Error (detail) message Error: Payload encoding error: Cannot construct STArray from value given
Causing error message: Cannot construct STArray from value given

BURN_ADDRESS = 'rhJYDuVMQxabTyiWuHQkQyDxr6uZEdpv5u'  
export const getQR = async (avax_address: string, amount: string) => {
  try {
    const hex_avax_address = Buffer.from(avax_address)
      .toString("hex")
      .toUpperCase();
    const request = {
            TransactionType: "Payment",
            Destination: BURN_ADDRESS,
            Amount: {
              currency: 'MLD',
              value: amount,
              issuer: BURN_ADDRESS,
            },
            Memos: [
              {
                Memo: {
                  MemoData: hex_avax_address,
                },
              },
            ],
          };
    const payload = await Sdk.payload.create(request, true);
    return {
      link: payload?.next?.always,
      qr_code: payload?.refs?.qr_png,
    };
  } catch (error) {
    console.log(error);
    return null;
  }
};