Steps to reproduce:
1. Log in to nightly
2. Create user with Editor role
3. Navigate to Content tree -> Create a draft article and assign to another user for review
4. Log in as the editor user and, from Dashboard, open the article for review
5. Make changes, and try to reassign back to the original author

Expected result:

• A list of users appears as you type

Actual result:

• The list of users does not appear