Signcolumn \ quickfix empty despite errors reported by langserv

[Anrock]

neovim version: v0.2.3-271-g1e68e0630
Minimal vimrc:

call plug#begin()
Plug 'autozimu/LanguageClient-neovim', {
    \ 'tag': 'binary-0.1.8-x86_64-pc-windows-gnu'
    \ }
call plug#end()

let g:LanguageClient_serverCommands = {
    \ 'haskell': ['hie', '--lsp', '-d', '-l', 'D:\Temp\hie.log']
    \ }
let g:LanguageClient_loggingLevel = 'DEBUG'

Language server name:
https://github.com/haskell/haskell-ide-engine @ 3ec8e93e9ca751cf282556998851ffa65f32e06b with haskell-lsp dep override to https://github.com/alanz/haskell-lsp @ 4462fa7a97e99cba954cfbce27b63363cd3f06c9

Reproduction steps (from clean state):
1. Install plugin
2. Open file (with .hs extension) with contents:

main :: IO ()
main = putStLn "hello"

Expected: error sign on second line and error entry in quickfix list
Actual: signcolon and quickfix list empty.

Logs:
LanguageClient.log
LanguageServer.log: empty
hie.log - langserver binary log