Foliage in the Foliage mode panel can be checked on and off, to change which ones are active and being painted.
Currently, the checkmark is only visible on hover, and otherwise the only indicator that a foliage actor is active is a slight change in the thumbnail brightness. This doesn’t work well when you work with diverse assets with varied colors and brightness levels at the shader/texture level. It can be impossible to tell at a glance what foliage is active without selecting everything so you can see the checkmarks.
I’d like to request that the checkmark remain visible when you’re not hovering over foliage, or some other clearer visual indicator of which ones are active (a colored outline, a change in background color, etc.).
Looks like this is an issue stemming from UE5 forcing black thumbnails with all assets. I spent a few hours digging for a thumbnail fix and then it also fixed this foliage tool hover/selection bug. Selected foliage has a lighter thumbnail but when it’s black on black, it’s not visible.
Here’s how to lighten your thumbnails:
In your Content Browser settings enable “Show Engine Content”
Scroll down to the Content Browser Engine folder, search for both FloorPlaneMaterial and SkySphereMaterial
When you open each of these you can manually adjust the Base Color. The FloorPlane will be most of your thumbnail, the SkySphere is the top little bit of the thumbnail. You can set these however you’d like but FloorPlane 0.1 and SkySphere 0.12 is a pretty decent medium grey.