1. Which version of LR?
2. Are you in Develop or Library?
3. How exactly are you "scrolling" through the presets -- hovering over the preset or clicking it?
Lightroom CC, In Develop, hovering over the preset.
It also occurs if I use a preset, move on to another image, then try to scroll through the presets. No change in the preview.
But using the graphics processor is supposed to be a feature of LR that is a benefit. Isn't it a bug if it does this while using the graphics processor?
When you disable the graphics processor, does the problem go away?
It's definitely a bug, very possibly related to this plugin bug reported in the official Adobe feedback forum: Lightroom SDK: photo:applyDevelopPreset() doesn't update Develop display when GPU enabled. Unfortunately, I can't reproduce the symptoms you're experiencing.
It's important to get a bug report filed in the feedback forum to call Adobe's attention to the issue. (They generally don't pay much attention to bugs plugins experience with the Software Development Kit, but they do pay more attention to end-user bugs.)