when trying to copy (or cut) and paste inside the ckeditor, the page flash and paste doesn't work.
I tried to download last version of ckeditor and change the library inside the grocery crud enterprise assets folder.
This fixed my problem and paste work as expected ( another window shows up and ask to paste the text again).
I suggest you to update the ckeditor library to fix the problem.
If anyone have this problem, i just fixed it like this :
1) downloaded the standard version of ckeditor
2) decompressed the folder inside assets/grocery-crud-enterprise/js/libraries folder
3) renamed the file jquery.js to ckeditor.adapter-jquery.js, inside the "adapters" folder of ckeditor
4) moved that file in the main ckeditor folder (check the folder inside grocery crud to understand the folder structure)