per_page doesnt work on me..

Thanks for the link. It may be a conflict with BWP Minify. Please deactivate that and your caching plugin temporarily and try the page again.

And update this plugin to version 1.15.4.

Try adding

wpmtst-pager-script

to the “Scripts to NOT minify” setting on the BWP Minify > Enqueued Files tab.

adding wpmtst-pager-script

to the “Scripts to NOT minify” settings works!

thanks