Another follow up with a solution, hopefully this helps someone – the first “while” was producing an infinite loop: <?php while ( have_posts() ) : the_post(); ?>
Once that was removed I managed to make this working, here’s the full code:
<?php
$i = 0;
?>
<div id="team" class="d-none d-md-block m-t-90 p-b-100 border-bee border-bee-vertical border-bee--gray border-bee--left"></div>
<div class="container">
<?php
// check for rows (parent repeater)
if( have_rows('about_team_sections') ): ?>
<?php
// loop through rows (parent repeater)
while( have_rows('about_team_sections') ): the_row(); ?>
<div class="row team-row">
<?php
// check for rows (sub repeater)
if( have_rows('team_section') ): ?>
<?php
// loop through rows (sub repeater)
while( have_rows('team_section') ): the_row();
// display columns
?>
<div class="col-md-4 ab-team-item">
<div class="ab-team text-center" data-id="<?=$i?>" data-scroll-animate="fadeIn">
<div class="ab-team-image">
<img src="<?=\AB\Template\get_image_url(get_sub_field('image'))?>" alt="">
</div>
<div class="ab-team-content">
<div class="ab-team-name font-windsor-bold fs-21"><?=get_sub_field('name')?></div>
<div class="ab-team-position text-uppercase fs-12 letter-spacing-200"><b><?=get_sub_field('position')?></b></div>
<div class="ab-team-social-media">
<ul>
<?=get_sub_field('social_media')?>
</ul>
</div>
</div>
</div>
</div><!-- end .ab-team-item -->
<?php endwhile; ?>
<?php endif; //if( get_sub_field('team_section') ): ?>
</div>
<?php endwhile; // while( has_sub_field('about_team_sections') ): ?>
<?php endif; // if( get_field('about_team_sections') ): ?>
</div><!-- end .container -->
