The most common cause of this symptom is that the data does not stop, but lands instead at an odd place in time. I suggest using an alltime-realtime search at the problem time to review the data, or else simply searching all time for your data to find data in the future or spikes in the past to see where the data might be landing.
If that is the cause, frequently adjusting TIME_FORMAT to more accurately reflect the timestamps in your data is the solution.
There are other possible problems but they are hard to imagine from the description. This might become a support issue.
The original poster hasn't been around for 2 years. If you have this issue, it would get you much faster and more helpful results to post your own description of your current issue, and then answer the responsive questions and comments from the community about your issue.
Maybe I not understood good, but after searching (hours after 4:00 Sun) it matching 0 events, till time when I "modify" sourcetype (i checked that only save is nessesery). Recently I upgraded to 6.2 version, but no change of this symptoms.