Monodevelop doesn't highlight/autocomplete UnityEngine words

Hello!

I am a beginner in Unity + MonoDevelop. I have started writing some basic scripts, but noticed that the autocomplete and highlight options don't work on "GameObject" and similar items which belong to the UnityEngine.

It automatically adds the "using UnityEngine" line so this is not the problem.

Could someone give me a tip on this one?

C# words work perfectly.