Activating a virtual environment in Windows doesn't change the build system

[SBuercklin]

I have Anaconda installed with Python 2.7 on Windows 10, and I created a virtual environment that uses Python 3.5. If I activate the Python 3.5 virtual environment within SublimeText and run the following code

import sys print(sys.version)

I get the following output

2.7.12 |Anaconda 4.2.0 (64-bit)| (default, Jun 29 2016, 11:07:13) [MSC v.1500 64 bit (AMD64)]

which is obviously not Python 3.5. Opening a command prompt, activating my Python 3.5 virtual environment, and executing the same code yields

3.5.3 |Anaconda 4.4.0 (64-bit)| (default, May 15 2017, 10:43:23) [MSC v.1900 64 bit (AMD64)]

Additionally, I've saved the Sublime Project to see if it's setting the virtual environment correctly, and it appears to be

"virtualenv": "C:\\Users\\My Name\\Anaconda2\\envs\\python3env"

What might be prohibiting my SublimeText installation from building with the alternative environment?