CC2640R2F-Q1: Observer: Continuous scan for iBeacon's

Part Number:CC2640R2F-Q1

Hi, I am using simple_peripheral with PLUS_OBSERVER to scan for iBeacons. I am getting a few GAP_DEVICE_INFO_EVENT in SimpleBLEPeripheralObserver_processRoleEvent and see my iBeacons in gapDeviceInfoEvent_t.pEvtData. However, after some time, I stop getting callbacks. I have verified that my iBeacons still advertise, but my observer seems to no longer see them. 

I am assuming that this may be related to DEFAULT_MAX_SCAN_RES? I tried setting this number to 0 but that just turns off the discover altogether. Higher numbers seems to give me more callbacks longer but eventually also stop. 

How can I configure my observer so it will scan iBeacons indefinitely? 

Thanks.