Our Google Sheets connector is importing your data based on if it detects new changes has been made in the sheet or not. If it can't detect any changes, then nothing will be updated.
Google does not update the time when the sheet was last modified if you have a lookup or import of another sheet in your connected Google Sheet.
That means that if you have a Google Sheet with some sort of lookup/import formula like =IMPORTRANGE or similar, then that data is not reflected in the Google Drive API that we use to check if a spreadsheet has been updated.
If you have a setup like this, please reach out to Support who can assist with implementing a workaround.