SQL Job schedule got disabled

Hi,

I am trying to investigate why

all jobs for a particular database were detached from schedule (though jobs were not disabled) but did not trigger having no schedule. (I have attached a screen shot, to identify the Enable check box)

Any thoughts to investigate where shall I look. I could not find any clues from default trace, but have saved default trace into a table

Onwards I am going to setup an Audit.

Hint.

any changes in schedule will modify "msdb.dbo.sysschedules" and we can find the last modification but unable to check previous -- we should have some thing in default trace data.

select name, date_created, date_modified from msdb.dbo.sysschedules where CAST(date_modified AS DATE) = '2022-10-06'