SpaceVim and YCM on MacVim with a specific interpreter

[Oleksandr Nikolskyy]

GM
I'm using spacevim from macvim and first use case is python (using project-specific venv).
However I experience a strange behaviour: ycm autocompletes relative imports. However doesn't seem to recognise installed python packages. I've created a project-specific init.toml as suggested and specified the python interpreter from the corresponding virtual environment.
Now the interesting thing is: when I launch vim from terminal, autocompletion works, when I work from macvim it does not.

I am crossposting this from their Gitter, because I'm not sure if the issue comes from MacVim or from SpaceVim.