Service now event data is missing in Splunk

Hello Team, I have Splunk enterprise vesion 6.1.8 and Splunk App for ServiceNow (App Version 2.4), all servicenow data is coming into the splunk but found that some of data (Snow_Events)is missed, so how we can track or debugging the issue here? or shall we get any log error entry? so that we found what the issue? Thanks