List Org Sheets api not listing all sheets

I need to fetch list of all sheets that have changed since a particular time, therefore on using the modifiedSince parameter, but the list returned is not consistent.

I am not receiving any data sometimes even after performing an edit adding data to a cell (row/column), and sometimes it does come up.

Is there any refresh time for updating this data in the api response ? Also why is there this inconsistency.? Is there any other way to fetch this list.

The api i am using is