Watcher log history not available for some watchers scripts

Hi,
I am currently facing issue with the watcher logs, currently I am using ELK version 7.11 and when I check Execution history of some watcher for last 1 hour, 1 day or even last week , no logs are available. For few watchers we can see the history but for few we cannot. Is there any known bug for watcher in this version?