Cmd+Backspace and Cmd+Delete bugs

Hello,

Every app on every OS has a way to traverse/select and delete whole words to the right and to the left of the insertion point. E.g. InDesign/Story Editor/InCopy allow you to traverse[/select] words to the right by Cmd[+Shift]+Arrow Right and to the left – with Cmd[+Shift]+Arrow Left. InDesign and Story Editor also allow you to delete words to the right and words to the left with Cmd+Delete and Cmd+Backspace.

But, most unfortunately, and contrary to InDesign, Story Editor and all other apps on Earth, InCopy acts erratically when one tries Cmd+Backspace or Cmd+Delete: sometimes they delete a word to the left, but sometimes they delete a word to the right!

This is me hitting ONLY Cmd+Backspace:

This is me hitting ONLY Cmd+Delete:

I have checked CS5.5 and CC2018 (13.1) on OSX10.11. Is this a known bug? Am I missing something?

Regards

m.