Okay I find out why the plugin wouldn’t compile.
With @RecourseDesign answer’s, I find a previous post here which says:
…Or this might be also some improper include. You said you place Engine.h in some file, Engine.h should be included in TestPluginPrivatePCH.h as a first include + if you include something else from engine it Engine.h is sometimes ingerented from there
That was it. I included Engine.h in the beginning of my Ariel.h header file and the build succeeded. I assume that this wasn’t a problem when compiling through the unreal editor because Engine.h was already added the linker by some other unreal script, but it wasn’t the case when packaging the plugin independently.
It’s funny because my IDE (Jetbrain Rider) say that the include is unused but it’s not really the case.