Cannot use the edit feature in Photo app
When I launch Photos app my library is normal and intact. When I try to edit an image I click on Edit button. Very very briefly the list of Edit options will pop up and then just go black again. Cannot access any Edit features at all. Have tried to Repair Library, hasn't helped.
Using 10.10.3.
iMac, OS X Yosemite (10.10.3)