WP Smush Pro not working correctly

My WP smush Pro app is not smushing all my images at once. Sometimes it smush 10, somethiomes 49 (maximum), sometimes dosnt work or just one... and the stop. Its frustating. Any idea what can be wrong with it.

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WP Smush Pro

Settings

Smush images on upload PRO FEATURES
Smush Original ImageSuper-Smush images (Lossy Image Compression)Enable NextGen Gallery integrationBackup Original Images (Will nearly double the size of your Uploads Directory)
Save Changes
Smush in Bulk

Please be aware, smushing a large number of images can take a while depending on your server and network speed. You must keep this page open while the bulk smush is processing, but you can leave at any time and come back to continue where it left off.

Reduced by 671.95 MB ( 66.72% )
260 of 1570 total attachments have been smushed

Smushing in Progress
You can also smush images individually from your Media Library.