"Add New" menu not functioning correctly on OSX

The editor menu that comes up when you click “Add New” in the content browser, or right click inside the content browser, doesn’t remain open as I try to select the upper entries on OSX in 4.18 Preview (1 and 2). I can navigate through the “Create Advanced Asset” section at the bottom without a problem, but as soon as my cursor goes above that section from below, the menu closes. If I move the cursor out to the left, avoiding the spot where “Create Advanced Assets” meets “Particle System”, then I can reach those upper icons without the menu closing.

This is still happening in Preview 3

This is resolved in 4.18 Preview 4