No highlighting for strings with '\n'

I am developing eo-intellij-plugin. I have this code:

[] > main
  "abc \n" > @

The problem is that "abc \n" is black (should be green because it is string). Problem appears only if I use special symbols like \n.
When I set cursor before this string and then type backspace and space string is highlighted correctly (it becomes green).
However the parsing seems to be correctly in both cases and I even see green daw in top right corner, it means indexing was successful.

I tried to reproduce it with other plugin, I cloned antlr example plugin and I faced same problem with string highlighting
Any ideas why this may happen? Is it problem of ANTLR or an IDE bug?