using Bootstrap Accordion with Wordpress ACF repeater fields - wordpress

Question

I am using Bootstrap Accordion with ACF and have a repeater in a repeater section. I get all the data and it is displayed as it should be but when I click on the title to open the body the class changes to "collapse show" and the accordion opens for a fraction of a second only to close again immediately. Does any one have any ideas? Here's the code:
<div id="accordion">
<div class="card">
<?php
if( have_rows('instructions_android')):
$i = 1;
while ( have_rows('instructions_android')) : the_row();
?>
<div class="card-header" id="heading<?php echo $i; ?>">
<h5 class="mb-0">
<button class="btn btn-link collapsed" data-toggle="collapse" data-target="#collapse<?php echo $i; ?>" aria-expanded="false" aria-controls="collapse<?php echo $i; ?>">
<span class="instr-title"><?php echo get_sub_field('etape_installation_no'); ?> : </span><span class="instr-title"><?php echo get_sub_field('titre_du_step'); ?></span>
</button>
</h5>
</div>
<div id="collapse<?php echo $i; ?>" class="collapse" aria-labelledby="heading<?php echo $i; ?>" data-parent="#accordion">
<?php
$i++;?>
<div class="card-body">
<ul>
<?php
$j = 1;
if( have_rows('descr_step')):
while ( have_rows('descr_step')) : the_row();
?>
<li><?php echo get_sub_field('description'); ?></li>
<?php
$j++;
endwhile; ?>
</ul>
<?php endif; ?>
</div><!--card body-->
</div>
</div><!--card-->
<?php endwhile;
endif;?>
</div>