[Theme: Portafolio] Pagination broken with #038; instead of &

I am using Portafolio by WPExplorer for a while, everything was fine, but suddenly the complete pagination is broken.

Might this have been caused by a recent WordPress update?

1st page is working:
?post_type=portfolio

2nd page is not working anymore:
?post_type=portfolio#038;paged=2

instead of / should be:
?post_type=portfolio&paged=2

I did never change any entries at Portafolio: pagination.php (functions/pagination.php), which are the following:

if( !$current_page = get_query_var(‘paged’) )
$current_page = 1;
if( get_option(‘permalink_structure’) ) {
$format = ‘page/%#%/’;
} else {
$format = ‘&paged=%#%’;
}

Well, I am absolutely not an expert in this code things – do you have any idea, what this might be about? :-/

Thanks a million!