Why is adding texture to atlas not lowering memory consumption?

Question

I have a NPOT sprite used in UI and Unity previews it like this:

When I add a Packing Tag to it Unity displays this:

Notice that Unity keeps saying it takes 8.2MB. I thought it would be lesser but when profiling my app I saw it does take 8MB.

The texture is NPOT so I was expecting this to lower when adding to a sprite because of the PVRTC compression. It is 1399x2048 so it should fit in an atlas 2048x2048 PVRTC which would take about 3MB. Why is this not happening?

I'm using Unity 2018.1.7f1 and the legacy Sprite Packer is disabled.

Answer 1

I found out what's wrong. It was partially my misunderstanding of how the Sprite Packer works and partially Unity's fault:

As I said in my question, legacy Sprite Packer is disabled. Packing Tags work with the legacy Sprite Packer. My project is set to use the new Sprite Packer which should use .spriteatlas files to create atlases (more info here), therefore no atlases were being created.

It's partially Unity's fault because it incorrectly shows me "Compressed PVRTC" in the Preview window, which leads me to think that it's being packed.