Mashup map > post__in not working

Dear,

I am using the mashup functionality. I allow visitors to make a search on zip and another variable. I obtain the post IDs of the result of the query and I want to display the search result on a mashup map, but the pronamic mashup code doesn’t work with post__in neither include.
My search result returns a string of following post ids : 3901, 3900, 3898, 3703, 3699, 3519, 3470, 3912.
post__in requires an array. To convert my string to an array I use following code:
$googleIDS = explode(', ', $string); But it doesn’t work.
If I hard code the array as follow
array(3901, 3900, 3898, 3703, 3699, 3519, 3470, 3912) then it works.
I also tried to replace 'post__in' => $googleIDS, by 'include' => $string, but it doesn’t work neither.
Here is my code

if ( function_exists( 'pronamic_google_maps_mashup' ) ) {
pronamic_google_maps_mashup(
array(
'post_type'      => 'cpt',
'post__in'	=> $googleIDS,
),
array(
	'width'          => '100%',
	'height'         => 400,
	'map_type_id'    => 'roadmap',
	'marker_options' => array(
		'icon' => 'https://www.mywebsite.com/mymarker.png',
	'latitude'       => 52,
	'longitude'      => 8,
	'zoom'           => 4,
	'fit_bounds'     => false,
	),
)
);
}
}
showProfessionnels( $atts );

Any help hardly appreciate.

https://www.ads-software.com/plugins/pronamic-google-maps/