Detail-preserving upscale making 0 improvements to the video, only scaling it up.

Greetings, 

I decided to upscale a video of mine through Detail-preserving upscale, but it simply does not work. I created a 4K Composition, placed the 720p video on the timeline, put Detail-preserving upscale and changed it to "300%". It scaled up, but quality-wise it looks exactly the same. I even created a second layer and tried to analyze the differences between the one with the effect and the other with only regular scaling. No difference. 

Any ideas of why that could be happening? Thank you!