Wordpress Plugin Install - Nginx 400 Bad Header


I have Flywheel installed on a Windows 10 Pro machine. I have a custom install using the latest PHP/MySQL and with Nginx as web server.

Site loads ok and I can access admin. Randomly when uploading plugins I receive a 400 Bad Header from Nginx 1.10.1. Sometimes plugins upload and install.

I cannot see where there is an issue and I do not know what this error means or where I can go to try and troubleshoot or debug the issue. Any help would be most appreciated.