Do you think we are all mind readers out here?
What version Photoshop and what computer hardware platform are you using?
And what OS version?
I have the same problem since I installed the latest version av Photoshop CC on myc Asus computer with 8 GB RAM and Windows 10. In the former version of Photoshop I could use this option very effective. I have canceled the version and made a new install and nothing happened.