When modo first opens an .lxo file it tries to look for any texture images attached to that scene. If you happen to move your scenes across different machines that have different paths set-up, modo won't always be able to automatically find your texture files. Instead, sometimes it will ask you whether you want to search for them.

Because modo stores image textures under the \Library\Application Support\Content\Assets\Images,  if you try to locate a file saved here using Spotlight, you'll get no results because that folder is restricted from being searched. Two ways to get around this...

• Navigate to your Contents folder and then perform the search, narrowing it down by folder and file name. I actually have a link to my images folder in my Finder sidebar
or
• In the spotlight search bar, type in  Filename:"brick_bump.png"