I can see that you are trying to run the report from 1st September till 18th September in one go. What if you try to run the report in several intervals such as 1st till 5, 5 to 10 and so on. Maybe you can try to run the report for each single day and try to narrow it down that way as well. Please be aware of below defect as well that is causing issues in running reports as well these days, worth checking with TAC
https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvb27878
Regards
Deepak