More than likely the plugin is not saving the information that ACF needs to map the fields. The pluign you’re using is probably inserting the postmeta for the field correctly, but not the field that tells ACF how to treat that data.
For every postmeta field ACF has an accompanying field.
Lets say that your field name is “my_field” and the ACF field ID of that field is something like “field_123456789abcdef”
ACF will save another postmeta field named “_my_field” with a value of “field_123456789abcdef”
This second field is not saved until you actually edit and save the post. The author of the plugin you’re using would need to take this into account.
Rather than using the acf function get_field(), or the_field(), you can use the standard WP get_post_meta() function to get the value you’re looking for.
