display info on hover not working when ambiguous definition occurs

Steps to reproduce this problem:
1. create a single .hs file
2. import some module and define a function whose name collides with a function in the module.
3. save the file and **restart** VS Code

In my case, it does highlight the error that ambiguous definition occurs, but it seems that the extension is not inspecting other parts of the code. When I hover on a function or a variable, it shows an empty small window instead of the definition.