Photos.app creates blank images after importing iPhoto library
I have the same problem. It turned out that the photos were gone, recovery had to come from a backup.

You can check if you have the same problem by right-clicking a white photo. Then copy the photo name. Then open a terminal and execute the following commands: cd ~/Pictures; find . -iname &lt;photo name&gt;. If nothing is found, you'll know the photo is gone :(