I don’t have enough rep to comment, but what does your actual query look like?
Edit: I haven’t been able to test it, but I think this will work
$args = array(
'post_type' => 'slider',
'meta_key' => '_thumbnail_id', // only pull sliders with images
'tax_query' => array(
array(
'taxonomy' => 'slideshow',
'field' => 'slug',
'terms' => 'homeslide',
'operator' => 'IN'
)
)
)
$query = new WP_Query( $args);
Then follow the normal loop