Thank you for using Mighty Addons. I just tested the Cross-Site Copy/Paste extension on three different sites. Here’s a screencast.
This is tested on 3 different domains namely, Statistical Bird, Innovative Stag, Yawning Xenomorph.
It’s working fine at our end. There must be some conflict with another plugin.
Can you share your site’s credentials at [email protected], so, I can have a look?