If a keyword fails to display your ads, it's possible that negative keywords are to blame. Negative Keyword Conflicts identify overlapping negative keywords that are keeping targeted keywords from bidding so you can review and remove them.
How to resolve keyword conflicts
Option #1: Workshop
Resolve negative keyword conflicts via Negative Keyword Conflicts notifications. Use the Workshop feature to modify, pause, or delete negative or targeted keywords.
Option #2: Manage
You can also resolve keyword conflicts in Manage:
Go to Manage (globe icon) in the left menu.
Select Accounts.
Click on an account from the list.
Go to Settings & Tools under Account Actions near the top.
Choose Keyword Conflicts in the settings drawer menu.
Click the > icon next to the negative keyword to reveal the blocked content.
Select the checkbox(es) next to the keywords you want to remove.
Click Remove # Keyword Conflict in the blue bulk edit menu.
This action will delete the negative keyword, and it will no longer prevent the targeted keywords from bidding. The negative keyword will be removed from all instances where it was applied. For instance, if your negative keyword is part of a shared set, it will be removed from any location where you've used that shared set.
Note: You can also see if a keyword has conflicts by navigating to the keyword section of an account. The status of the keyword will be bright red and read Conflict. Once the negative keyword is removed, the conflicted keyword will have a green status of Eligible.