People analysis in FCPX import may be buggy???

I have an event in a stock image library that is comprised of about 2000 graphic elements, mostly png or jpg images. Upon import I selected to do a people analysis on these images. After import all the image thumbnails showed properly in the event browser, and FCPX fairly accurately created 1 person, 2 person, wide, etc. categories for these images. Once I clicked on the people collection to view these and then returned to the top level of the event to show all images, nearly all of the thumbnails were blank until I moused over them. I deleted the event twice and reimported twice and this issue seems to be consistent. Maybe the analysis is not intended for still images. Anyone experience this?

UPDATE - after a reboot and restart of FCPX now all is working properly. So the analysis does work correct for still images.