New Replication Job Fails after 90 Minutes with Account Not Found

I had a replication job running fine that I once set a bandwidth throttle to 5MB/s and I curiously could never, ever change. I would change it in the job settings, change it to 0.0 or 15 or 50 and hit apply, and when it ran it would always go back to 5MB/s. I would go back into the job settings immediately after changing it and it would have reverted back to 5MB/s.

Instead of troubleshooting that, I instead created a new job (not cloned the old one), added the same client, same settings for everything, except this time I put the Throttle at 15MB/s.

Unfortunately, it runs without a problem for about 90 minutes out of a 12 hour window and then errors out with:

2016-11-30 23:44:17 avtar Error <8608>: Failed to complete backup; Account not found in the Avamar database. (MSG_CMD_ACCESS_CHILD=47 serial=1030318 seq=0 flags=RU:N:1 kind=2 rsp=MSG_ERR_ACCOUNT_NOT_FOUND retries=0)

2016-11-30 23:44:17 avtar Error <15085>: Backup not completed properly on server.

2016-11-30 23:44:17 avtar Error <5672>: Could not record backup on target server ()

Looking at the log files, it is indeed replicating various files for 90 minutes before this error occurs. If it was a permission or account error, it would error out immediately instead of after 90 minutes. Strangely I have let it run for 3 nights in a row and it always times out at about 90 minutes.

Any ideas what the problem is?