ACF fields only display on new posts, not old updated posts

Hi guys,

I have a strange issue where, perhaps after a recent update, ACF fields that I had in place don’t show on old posts anymore, but work/display correctly on any new posts created.

I’ve already deactivated all plugins to see if there was a conflict but same results. The code I use below has worked perfectly for a few years now, but now only works on new posts:

<?php if( get_field('coach_tour_availability') == 'soldout' ){ ?>
/* Do something */
<?php } elseif( get_field('coach_tour_availability') == 'waitinglistonly' ){ ?>
/* Do something else */
<?php } else { ?>
/* Otherwise do this */
<?php } else {} ?>

Any ideas why this would only work on new posts created now?

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