Sorting only works page by page

hello,

#10 solved the pager issue for me but a bug steel remains on a table views sortable by php_code field :
sorting the view using the php_code field (date field Y-m-d) does not work. Pricesly it works only page by page :

page 1
2015-05-10
2015-05-20
2015-10-22
2016-01-21
2016-02-12
...

page 2
2015-05-09
2015-05-11
2015-05-29
2016-01-09
2016-03-08
...

page 3
etc

i tried numerical sort, and natural sorting on field settings