vscode-python: Symbol navigation via ctrl-t does not work when the microsoft language server is enabled (jedi disabled)

Environment data

• VS Code version: 1.27.2
• Extension version (available under the Extensions sidebar): 2018.8.0
• OS and version: Ubuntu 16.04
• Python version (& distribution if applicable, e.g. Anaconda): 3.6 or 3.7 built from source
• Type of virtual environment used: virtualenv / python -m venv
• Relevant/affected Python packages and their versions: N/A

Steps to reproduce:

Disable jedi in settings.json. Here the full settings.json I used to make sure that this issue is not caused by a problem in my config:

{
    "python.jediEnabled": false
}

Then try with the following mixed Python/Cython/C/C++ code base:

$ git clone https://github.com/scikit-learn/scikit-learn
$ cd scikit-learn
$ code .

Then hit “ctrl-t” and type “KMeans” for instance.

Actual behavior

The ctrl-t menu is never populated as expected (it stays empty). I have the same problem with other symbols defined in this project (e.g. LogisticRegression, check_array…).

The “Analysing workspace, 1 item remaining…” message never goes away.

Weirdly enough, hitting “F12” on a Python symbol defined in the workspace can make VS code navigate to it successfully. It’s just the ctrl-t symbol search menu that’s broken.

Expected behavior

Being able to open the k_means_.py file from the project folder in the workspace to navigate to the definition of the KMeans class.

Logs

Output for Python in the Output panel (View→Output, change the drop-down the upper-right of the Output panel to Python)

Starting Microsoft Python language server.
Initializing for /volatile/ogrisel/.virtualenvs/py36/bin/python
##########Linting Output - pylint##########
[snip]

[Error - 09:52:35] Request workspace/symbol failed.
  Message: Object reference not set to an instance of an object.
  Code: -32000 
[object Object]
[Error - 09:52:36] Request workspace/symbol failed.
  Message: Object reference not set to an instance of an object.
  Code: -32000 
[object Object]
...

Output from Console under the Developer Tools panel (toggle Developer Tools on under Help)

[nothing]

Also note that jedi has no problem with this workspace.