Steps to reproduce

1. Insert the following in Wiki Markup Editor:

   * Item 1
   ** Sub-item 1
   * Item 2 (/)
   ** Sub-item 2
   * Item 3 (y)
   ** Sub-item 3
   * Item 4
   ** Sub-item 4
   

   

2. Save the page which will result like the following:
   
3. Edit and switch to Rich Text Editor:
   
4. Switch back to Wiki Markup Editor:
   
5. Save the page which will result like the following:
   

Workaround

Adding double backslashes after the emoticon seems to resolve the issue.

* Item 1
** Sub-item 1
* Item 2 (/)\\
** Sub-item 2
* Item 3 (y)\\
** Sub-item 3
* Item 4
** Sub-item 4