We have got the reason why the plugin can not be compiled successfully after update UE from 5.3 to 5.4, it's that the plugin's source code are excluded from unity build since 5.4.
We forced the plugin to build with Unity blob by changing the UBT configuration using the build configuration file under Engine\Saved\UnrealBuildTool\BuildConfiguration.xml.
Open this file and add the SourceFileWorkingSet section as in this example.
We have got the reason why the plugin can not be compiled successfully after update UE from 5.3 to 5.4, it's that the plugin's source code are excluded from unity build since 5.4. We forced the plugin to build with Unity blob by changing the UBT configuration using the build configuration file under Engine\Saved\UnrealBuildTool\BuildConfiguration.xml. Open this file and add the SourceFileWorkingSet section as in this example.
<?xml version="1.0" encoding="utf-8" ?>