@louiswalch – many thanks for this approach. Have updated to only auto-collapse repeaters in the admin area (working in ACF Pro – version 5.6.10)
function rdsn_acf_repeater_collapse() {
?>
<style id="rdsn-acf-repeater-collapse">.acf-repeater .acf-table {display:none;}</style>
<script type="text/javascript">
jQuery(function($) {
$('.acf-repeater .acf-row').addClass('-collapsed');
$('#rdsn-acf-repeater-collapse').detach();
});
</script>
<?php
}
add_action('acf/input/admin_head', 'rdsn_acf_repeater_collapse');