Describe the bug

Here's the recording.

https://share.wppopupmaker.com/qGu4WyJx

Most likely culprit.

Site information

Popup Maker version: 1.20.4

WordPress version: 6.7.2

PHP version: 7.4.33

Expected behavior

The columns should sort.

Current behavior

404s.

Steps to reproduce

1. Go to the Subscribers page.
2. Click any of the sortable column headings.

Here's a video of that.

https://share.wppopupmaker.com/qGu4WyJx

Errors

404s

E.g. https://http//wildebeest-take.instawp.xyz/wp-admin/edit.php?post_type=popup&page=pum-subscribers&orderby=fname&order=asc

Additional context