This looks to be still in deep alpha.

It initially listed a lot of processes, but failed to display anything in the three main columns (CPU, footprint, memory), and nothing at all in the details at the bottom.

Then, when the privileged helper was installed and approved through Login Items, nothing came up ever again. All panels of the window are now blank, even after a full restart of the app.

Edit: I did not build from source, I used the downloabable DMG from the release assets.