Asset Packages/com.unity.probuilder/Editor/MenuActions/Selection has no meta file, but it’s in an immutable folder. The asset will be ignored.
(Filename: C:\buildslave\unity\build\Modules/AssetDatabase/Editor/V2/GuidDB.cpp Line: 614)
I am new to Unity and have no idea how to solve it. I saw plenty of those meta files outside of the folders, but dragging them into the corresponding folders and removing the read only attributes did nothing.
You shouldn’t need to run Unity as Administrator at all but it is helpful to do it in some cases like yours in order to gather more information about the underline problem.
Now that you know that is a permission issue, you can try to move your entire project into another location where you are sure that the read and write are enabled in general.