The original report has screenshots in it.
- Select a section.
- Cut (Shift+Del) and put cursor in...
- ..."New paragraph" area.
- Paste (Shift+Ins). Notice "phantom" text has appeared below normal.
- Put cursor in "phantom" text. It has dssappeared.
- Press Del. Whole text has dissapeared! Uncaught errors in browser console.
- Undo didn't work either. More uncaught error in browser console.
Found and reproduced in Chrome 64.0.3282.186 / Windows 7 SP1