Hi Nigel,
Sorry for the delay in getting back to you. I have tried all suggestions highlighted in your post on 29th June and I still can't Windows Update to successfully download and to install updates i.e. keep getting error 0x800705b4 every time I click Check for Updates. All steps worked successfully including applying the latest Quality Update i.e. Recommended/Important Update as well as applying the latest Servicing Stack Update i.e. Security Update from the Microsoft website. I have even tried a third party software called WSUS Offline Update where the WSUS Offline Update Generator pulls the updates fine but is not able to apply them using the WSUS Offline Update Installer as this process unfortunately still relies on the Windows Update service. Also this utility only currently supports up to Windows 10 1909 so a lot of the updates for Windows 10 1909 wouldn't apply anyway even when applying manually. The only solution up to now is to download and to install the latest Quality and Servicing Stack updates from the official Microsoft pages. I am beginning to suspect whether it is the security software at fault here as I am nearly at a loss trying to diagnose this issue permanently. I even tried the built-in Administrator account and it too resulted in the same Windows Update error. The other thing I have noticed is the Application Identity service can't be started automatically as it results in an Access Denied message but can be started manually. I have noticed this on my PC but Windows Update works fine regardless with or without it. Anymore suggests would be much appreciated.
Kind regards,
RocknRollTim
P.S. There are occasions where Windows Update says it is has successfully checked for updates, this is without me pressing Check for Updates. Also there are occasions where the Windows Update history shows that updates have been successfully applied i.e. manually but then moments later it becomes all of a sudden blank.