Scheduled Report with inactive Creators are not working

Scheduled Report with inactive Creators are not working.

Steps to reproduce:

1. Create a new Admin user
2. Log in with this user and create a Scheduled report
3. With the original Admin user deactivate the new user
4. The Scheduled report won't run. An exception is thrown on the log file and the following error message appear on Audit Log "There are no issues to export. You must provide at least one."

I noticed some other problems while reproducing this Bug:
On the Scheduled reports page, the Creator and Last Modifier usernames are not correct