Azure Triggered Webjob and Oauth - aborting webjob - azure

Question

i'm having continual trouble keeping a triggered webjob up and running on Azure, after digging around in some logs i located one for the 'start' webjob it looks to me there is an authorisation on the service which is specifically scoped for the triggered webjob.
what i'm thinking is the authentication is expiring and not auto-renewing so the triggered webjob fails and moves to an aborted state.
we have already tried setting the configuration setting for the webjob to 12 months (in seconds) and we have applied a heartbeat, service still shuts down though.
log details below;
also does anybody know what e_exp is?
that roughly equates to 3 days in seconds
{
"authorization": {
"action": "Microsoft.Web/sites/TriggeredWebJobs/run/action",
"scope": "/subscriptions/some GUID/resourceGroups/.../providers/Microsoft.Web/sites/.../TriggeredWebJobs/Processing"
},
"caller": "some GUID",
"channels": "Operation",
"claims": {
"aud": "https://management.core.windows.net/",
"iss": "https://sts.windows.net/some GUID/",
"iat": "1537204596",
"nbf": "1537204596",
"exp": "1537208496",
"aio": "numbers and letters",
"appid": "some GUID",
"appidacr": "1",
"e_exp": "262800",
"http://schemas.microsoft.com/identity/claims/identityprovider": "https://sts.windows.net/some GUID/",
"http://schemas.microsoft.com/identity/claims/objectidentifier": "some GUID",
"http://schemas.xmlsoap.org/ws/2005/05/identity/claims/nameidentifier": "some GUID",
"http://schemas.microsoft.com/identity/claims/tenantid": "some GUID",
"uti": "numbers and letters",
"ver": "1.0"
},
"correlationId": "some GUID",
"description": "",
"eventDataId": "some GUID",
"eventName": {
"value": "EndRequest",
"localizedValue": "End request"
},
"category": {
"value": "Administrative",
"localizedValue": "Administrative"
},
"eventTimestamp": "2018-09-17T17:21:50.2300614Z",
"id": "/subscriptions/some GUID/resourceGroups/qcp-ghs-prd/providers/Microsoft.Web/sites/.../TriggeredWebJobs/Processing/events/some GUID/ticks/...",
"level": "Informational",
"operationId": "some GUID",
"operationName": {
"value": "Microsoft.Web/sites/TriggeredWebJobs/run/action",
"localizedValue": "Run Web Apps Triggered WebJobs"
},
"resourceGroupName": "...",
"resourceProviderName": {
"value": "Microsoft.Web",
"localizedValue": "Azure Web Sites"
},
"resourceType": {
"value": "Microsoft.Web/sites/TriggeredWebJobs",
"localizedValue": "Microsoft.Web/sites/TriggeredWebJobs"
},
"resourceId": "/subscriptions/some GUID/resourceGroups/.../providers/Microsoft.Web/sites/qcp-ghs-prd-ase/TriggeredWebJobs/Processing",
"status": {
"value": "Succeeded",
"localizedValue": "Succeeded"
},
"subStatus": {
"value": "OK",
"localizedValue": "OK (HTTP Status Code: 200)"
},
"submissionTimestamp": "2018-09-17T17:22:18.6120141Z",
"subscriptionId": "some GUID",
"properties": {
"statusCode": "OK",
"serviceRequestId": "some GUID"
},
"relatedEvents": []
}