I think your problem is in the 'product_tag' => array( $producttags ),
$producttags
is already an array, so in this case it gets nested into a sub array. Change your arg to the following instead:
'product_tag' => $producttags,
I think your problem is in the 'product_tag' => array( $producttags ),
$producttags
is already an array, so in this case it gets nested into a sub array. Change your arg to the following instead:
'product_tag' => $producttags,