.js files for SharePoint 2016 Display templates not created when html file is added

I've done this on other SharePoint web applications and it works fine. In this particular web application when I make a copy of a display template html file the corresponding .js file is not being created.

For example, I make a copy and add Item_Default.html from Display Templates > Search. As soon as I add it the .js file of the same name should be created, it's not. What process is not working?

I can verify site collection feature SharePoint Server Publishing Infrastructure is active and so are site features, SharePoint Server Publishing and SharePoint Server Standard Site Features.

I'm aware I can cheat and use another web application, but this is not an acceptable workaround as I'm constantly updating and testing options. When I save the html the .js file is not updated.

What do i need to do to get this working? I've tried iis reset and even a server reboot. Search works fine, display templates do not. It's also odd that in SP designer the templates are not visible. I can only see them through a mapped path or browser.