Pager doesn't work in views block if views php field is used
There is a patch for that: Pager disappears when Global: PHP used in Views 3.8 


  After upgrading from Views version 7.x-3.7 to 7.x-3.8, the pager was
  missing from all views that used Global: PHP fields.


If patch#6 does not work for you, just follow the links in comment#27