From your first screenshot it seems as if you were using JakeBeckers language server plugin. It is not under development anymore and probably will break with Elixir 1.10.
Instead you should install the fork which is actively maintained and got quick fixes to work with Elixir 1.10 within days after the problems have been identified.
Also, whenever there are problems marked in your code, make sure you check the problems pane in the VScode. It might give you additional details.
