This is happening to me also, but I'm on Windows 10.
It should be noted that I did NOT have this issue with the last site I built with Sage 9, beta.2 as it was on March 9th when I used Composer to create the project and Yarn to install dependencies.
However on April 20 I set up another project and installed the latest dev-master and changes to Blade templates were no longer being injected.
I just re-installed the entire project, since I saw there's a beta3 that came out the next day. I thought maybe that fixed the issue but apparently not.
The watch task appears to work otherwise. The styles and images all get injected. But when I make changes to blade templates, I have to hit refresh on the browser to see them.
If there's any other info I can provide to help, do let me know. I've gotten quite spoiled about having to hit refresh while developing.