IDEA with ruby plugin wont find ruby stdlib

Hi,

I used Rubymine a lot and now I'm trying Intellij IDEA with ruby plugin because I'm working on a project mixing (pure) ruby and python.

I successfully set up the ruby sdk (through docker):

But in my project Intellij IDEA can't find ruby stdlib extensions:

And this lead to false detection because he tries to find some classes definitions in gems:

I'm using IDEA 2017.3.5 with ruby plugin 2017.3.20171228 and my gems are well detected.

Any idea of what I missed in my configuration ?

If this one can help too:

Thanks for your help !