You should not use break inside of an acf repeater loop. Instead you should use a counter. Repeaters should always be allowed to loop over all rows.
$counter = 0;
while (have_rows('repeater')) {
the_row();
if ($counter) {
// already did output of first, skip the rest
continue;
}
// output first row here
// increment counter so that no additional rows are output
$counter++;
}