I saw this behavior associated with drops in host count.
This is potentially because of the following line:
`hostsAvail := nHostsFree + len(hostsSpawned) - distroQueueInfo.CountDurationOverThreshold`
This does not account for for task group tasks, which may not add to the grand total of QOS hosts spawned specifically to run long-duration tasks. That will cause hostsAvail to be lower than it should be, and therefore time_to_empty to max out due to hostsAvail <=0.