That is because on the site side, ACF will not apply the conditional logic (only in the admin side). You need to do it by “yourself” using normal PHP condition, just like this:
if (get_field('credentials') == 'expired') the_field('credentials_expired_date');
This way, the credentials expired date will only be displayed if the credentials field is set to ‘expired’.
ACF is not applying the condition when displaying the data on the site and it is perfect like this. It is up to you (your code, I mean) to choose if you want or not to display that date (also, the ACF conditional logic doesn’t affect if the ‘credentials_expired_date’ is stored or not, it is only affecting the displaying of the field in the admin area).
