Making Tax Digital

Hi,I have some problems getting MTD working with Quickbooks online, although it shows in the VAT screen that MTD is enabled. I am stuck with the We can't connect to HMRC error. I've followed all the trouble shooting solutions in the Help that I can see and I have a VAT return due (to 31st May 2022), but all that is showing is old return info. I only took over doing these accounts in the Autumn 2021 and submitted VAT returns manually via the HMRC web site until now, not using this VAT screen at all. What can I do to resolve the problem?