[Form Submissions] Data in export files NOT sorted by date time in descending order

Description

Steps to reproduce

1. Create a form with several elements.
2. Add the form to a page and submit 100 submissions.
3. Open [Form Submission View], click [Select All], click link [Select all 100 records] on the notification bar.
4. Export the file to XLSX format -> the data in the export file is sorted by date time in descending order.
5. Click link [Clear selection], scroll down to the bottom then scroll to the middle.
6. Export the file to XLSX format.

Note: The issue is also reproducible in other formats (CSV, JSON, XML).

Expected:
Data in export file is sorted by date time in descending order when scrolling up/down.

Actual:
Data in export file is NOT sorted by date time in descending order.