I've had similar issues. I can't load certain pieces of clothing into scenes which worked fine in PP2014, and PP11 can't locate the files associated with many other pieces of clothing. I'll direct PP11 to the proper directories, and usually the scene works, but if I save and re-load the scene, PP11 can't find the clothing again. This is honestly getting ridiculous. I wouldn't have upgraded if I knew there would be so many issues.