I have checked your site and found few custom codes. You have used this filter to modify – add_filter( 'wpuf_add_post_args', array($this, 'set_pending'), 10, 1 ); but you have inserted the priority below 10 and for this reason this issue is happening. Please set your priority more than 10.
Also, the post status changed to pending- This issue was occurring because you have enabled charge for posting but you did not configure your payment process. So, I have unchecked this option from Wp User Frontend->Settings->Payments.