Symptom

JIRA Service Desk and Redmine Importer are disabled after uninstalling JIRA Agile (See problem.png)

Step to Reproduce

This is how I reproduced:

1. Install vanilla JIRA 6.4.6 (current latest)
2. Install JIRA Agile 6.7.4 (current latest) at 'Find add-ons'
3. Install JIRA Service Desk 2.5.0 (current latest) at 'Find add-ons'
4. Uninstall JIRA Agile at 'Manage add-ons'

Findings

It happens if you install JIRA Agile and then JIRA Service Desk
It does not happen if you install opposite way (JIRA Service Desk -> JIRA Agile)