new lines created below tmux after reducing the bash window

[Nono-m0le]

Please fill out the below information:

• Your Windows build number: Version 10.0.17134 Build 17134

• What you're doing and what's happening:

• Open a WSL
• launch tmux by executing : tmux (having the normal tmux layout, with the green bar at the bottom) :
  
• Reduce the window
• Re-open the window
  => From this point, there is an extra line below the green bar and I can type on it, also the first line on the top (the prompt) isn't visible anymore.
  

• What's wrong / what should be happening instead:
  Reducing / expanding the windows shouldn't create this "extra line" below the tmux green bottom bar.
  It seems that the whole display is moved 1 line ahead.