Portfolio Filter error on Pagination

Hi Developer!

I use Portfolio Filter for my 3 categories each pagination page for 20 portfolio but it is not.
please check my demo on http://demo3.senseanddesign.com/sufficiency/social-activities/
and click on the 2 or 3 option of filter, the portfolio show only one or two portfolios.
but when you click on page 2 of option 2 or 3, more portfolios appear.
it should to appear 20 portfolios per page right?
Please tell me how to fix it.

Best regards,

Ticket