You need type casting for custom fields event-start-date and event-end-date. Then it will compare with time() & date() value. You need to add 'type' => 'DATE', in your meta query args. So your meta query will be like this:
switch ($print_type) {
case 'current':
$meta_quer_args = array(
'relation' => 'AND',
array(
'key' => 'event-start-date',
'value' => $current,
'type' => 'DATE',
'compare' => '<=',
),
array(
'key' => 'event-end-date',
'value' => $current,
'type' => 'DATE',
'compare' => '>='
)
);
break;
case 'upcoming':
$meta_quer_args = array(
'relation' => 'AND',
array(
'key' => 'event-start-date',
'value' => date(),
'compare' => '>=',
'type' => 'DATE',
)
);
break;
case 'past':
$meta_quer_args = array(
'relation' => 'AND',
array(
'key' => 'event-start-date',
'value' => date(),
'type' => 'DATE',
'compare' => '<',
)
);
break;
default:
$meta_quer_args = array(
'relation' => 'AND',
array(
'key' => 'event-end-date',
'value' => date(),
'type' => 'DATE',
'compare' => '>=',
)
);
break;
}