I did a search producing about 150 recipes, and wanted to review them quickly, so used the compressed display (which I think shows about 200 on a page). Toward the end, there was a recipe that I was pretty sure I'd cooked a few years ago, but the little chef hat symbol by it was grey like all the others.
I clicked on the recipe to check, and indeed I'd cooked it, bookmarked it so, and had even written a Note. Then I tried viewing the search list of recipes in the default, fuller display, and sure enough the chef hat for that recipe was now green. So the bug is only with the compressed display.
It's just a little thing, but for me, scanning a long list quickly is exactly when it's most helpful to have the green chef hat stand out, so I hope it's an easy bug to fix.