Lightroom Classic: "Not responding" on ctrl+shft+C in Library mode

Lightroom CC Classic (latest version - 7.1) systematically gives me "Not responding" on ctrl+shft+C in Library mode. And the whole thing freezes. I have to quit and restart.

I'm trying to copy settings from one photo to paste to several others.

This is a new issue... I've made no changes to the library.

Windows 10 Home, i7-6700, 32 GB RAM, Nvidia 1080 Ti (yes, GPU acceleration is turned OFF in Lightroom).

Thanks