Queue trigger not being executed as expected

#### Investigative information

- Timestamp: Current time is 23:33:27 UTC, Wednesday, 6 June 2018
- Function App version (1.0 or 2.0-beta): 1.0
- Function App name: bcs-live-preview
- Function name(s) (as appropriate): GeneratePreview
- Invocation ID: N/A
- Region: Australia East

#### Repro steps

Provide the steps required to reproduce the problem:

1. Monitor the queue that this function is consuming (generatepreview on bcsfiles)

#### Expected behavior

Queue is processed always
No poison records

#### Actual behavior

Queue is not processed
No poison records (good!)
Queue was processed yesterday but required a restart.

#### Known workarounds

A function restart seemed to fix this but only once.

#### Related information

Other functions working OK for us

Function Sig:

` [FunctionName("GeneratePreview"), Timeout("00:01:00")]
public static async Task Run(
[QueueTrigger("generatepreview", Connection = "AzureStorageConnectionString")] PreviewGenerationRequest request
)
{`

Start with the GeneratePreview entry point and its QueueTrigger("generatepreview") signature, then review how the Azure Functions host monitors and dispatches that queue. Reproduce the report using the listed function and queue details, checking behavior before and after a restart. Done means the queue is processed consistently without a restart or poison records.

Written by the indexing model from the issue text.