I've seen this problem in several places in our dev and test implementation of SharePoint 2013. Especially in sites where there has been a lot of testing where people uninstall and install apps.
The app seems to get stuck in that it's not really installed or uninstalled.
If i try to uninstall it with powershell I get the error:
Uninstall-SPAppInstance : Another job exists for this app instance. Please retry after that job is done.
The timer service is running and has been restarted. Any ideas on how to remove the app so it can be installed properly?