Nightly jobs not continually occurring on exchange server. They run for a few days or run sporadically and stop until the server is rebooted.
If you are running build 126.96.36.199, install patch P-001213. If you are not on build 188.8.131.52, upgrade the core. Contact support and ask for patch P-001213 to resolve your nightly job failure on your exchange server.
VIDEO INSTALL PATCH LINK: https://support.quest.com/appassure/kb/126791
For more information on upgrading your AppAssure Core to 184.108.40.206, please reference Knowledge Article 129085 - How to Upgrade the AppAssure Core.
For more information on the AppAssure Patching process, please reference Knowledge Article 126791 - Applying Patches to the 5.4.X Core.