I watched your video and tried this.Clicking in the empty area did nothing, but clicking on the text of the name of the preset did work as expected, and double-clicking also did.
I clicked in the empty area to show it wasn’t loading. As you can see at the end of the video, loading the preset with 6 Nebula instances takes quite a while
This is what i do in the video : i double-click on the name of the preset on the first try, and i click on the name then click on Add on the second try. Neither work…
I cannot reproduce ti neither on Mac or PC, some presets take a little bit longer to load than others but they eventually load, perhaps a second and a half but they all load, I tried MID track presets, audio track presets, instrument track presets.
Please start Cubase in safe mode and see if that fixes the problem.