When running Windows Update step in a task sequence(ZTIWindowsUpdate.wsf) on a Windows 10 2004 build, updates are found, but all of them are being skipped. This is not the case with a 1909 based OS. This seems to be linked to InstallationBehavior.CanRequestUserInput, this is setting bInstall to False for every update.
<![LOG[Start Search...]LOG]!><time="16:18:05.000+000" date="06-09-2020" component="ZTIWindowsUpdate" context="" type="1" thread="" file="ZTIWindowsUpdate"><![LOG[ SKIP - ca3bb521-a8ea-4e26-a563-2ad6e3108b9a - Microsoft Silverlight (KB4481252) - 12 MB]LOG]!><time="16:18:34.000+000" date="06-09-2020" component="ZTIWindowsUpdate" context="" type="1" thread="" file="ZTIWindowsUpdate"><![LOG[ SKIP - 2221dd34-39bb-4f16-b320-be49fe4a6b95 - Windows Malicious Software Removal Tool x64 - v5.82 (KB890830) - 29 MB]LOG]!><time="16:18:34.000+000" date="06-09-2020" component="ZTIWindowsUpdate" context="" type="1" thread="" file="ZTIWindowsUpdate"><![LOG[ SKIP - f36bfc14-dc6c-48eb-a76e-c21828bb4ff6 - 2020-06 Security Update for Adobe Flash Player for Windows 10 Version 2004 for x64-based Systems (KB4561600) - 21 MB]LOG]!><time="16:18:34.000+000" date="06-09-2020" component="ZTIWindowsUpdate" context="" type="1" thread="" file="ZTIWindowsUpdate"><![LOG[ SKIP - 5faf5c4c-fa1d-4adc-9d54-6fd6d21ab0e6 - Security Intelligence Update for Microsoft Defender Antivirus - KB2267602 (Version 1.317.1010.0) - 106 MB]LOG]!><time="16:18:34.000+000" date="06-09-2020" component="ZTIWindowsUpdate" context="" type="1" thread="" file="ZTIWindowsUpdate"><![LOG[ SKIP - 8ab1c3b3-511d-4e32-a7d8-75722464fa0f - 2020-06 Cumulative Update for Windows 10 Version 2004 for x64-based Systems (KB4557957) - 83 GB]LOG]!><time="16:18:34.000+000" date="06-09-2020" component="ZTIWindowsUpdate" context="" type="1" thread="" file="ZTIWindowsUpdate"><![LOG[Scan complete, ready to install updates. Count = 0]LOG]!><time="16:18:34.000+000" date="06-09-2020" component="ZTIWindowsUpdate" context="" type="1" thread="" file="ZTIWindowsUpdate">
So far I've only tested this in a VM.
Windows 10 Pro x64 build 2004
MDT build 8456