Missing attributes in layout editor in Android Studio

This happened to me today. It was very frustrating, my entire gradle got messed up for unknown reason. in build.gradle (Module: app), I had issues with

implementation 'com.android.support:appcompat-v7:28.0.0' .

I chose to suppress the warning at first, and they put

//noinspection GradleCompatible 
implementation 'com.android.support:appcompat-v7:28.0.0'

for me... Anyways, I replaced above line with

implementation 'com.android.support:appcompat-v7:26.1.0'

and changed my compileSdkVersion to 26 and the attributes in layout editor came back alive. so I guess that appcompat thing has to do with the layout editor.

This worked for me.

• Exit android studio then make the below changes.

• Go to C:\Users\UserName.android and rename the build-cache folder to build-cache.bak

• Go to C:\Users\UserName.AndroidStudio3.2\system and rename these folders

  caches to caches.bak

  compiler to compiler.bak

  compile-server to compile-server.bak

  conversion to conversion.bak

  external_build_system to external_build_system.bak

  frameworks to frameworks.bak

  gradle to gradle.bak

  resource_folder_cache to resource_folder_cache.bak

• Open the Android Studio and open your project again.

No IDEA annotations attached to the JDK 1.8 (C:\...), some issues will not be found