Search In the past days does not return results

This quite strange. I have been forwarding logs to graylog. I am able to search log for today and yesterday. But It does not return results in the past days

Hej @tessie

what is your retention strategy?
Since when did you insert logs?
Is your time (NTP) configuration right?

@jan The index retention strategy is delete. Have been logging since March 2017, The configuration I guess is IST.What is actually NTP