same get_posts function works diffrently in tag.php and functions.php

Hi,
I have a strange issue that i don’t really understand, I explain : In my tag.php, i have an infinite scroll with custom post types thanks to the active tag and ajax.

I do the same get_posts in functions.php in my ajax function :

$posts = get_posts( array(
    'post_type' => 'video',
    'posts_per_page' => 6,
    'paged' => 1,
    'post_status' => 'publish'
)) ;

This simple get_posts not returning same values !
I replaced ‘paged’ with ‘offset’ and nothing changed !
How it’s possible ? What i forgot ?
If i add ‘order’ => ‘ASC’ and ‘orderby’ => ‘ID’ for example, it’s the worst !
Any ideas ? Thanks for help me.