Hi @squarecandy
The ACF date time picker plugin is not supposed to be used with the newest version of ACF as it has the similar feature. It’s the same as the premium add-ons that are not supposed to be used with the PRO version. So you should disable that add-on to get the date time picker field working correctly.
That being said, I guess the plugin author forgot to add a compatibility with the old add-on. Could you please open a new ticket so it can be passed directly to the plugin author? You can open it here: https://support.advancedcustomfields.com/new-ticket.
Thanks 🙂
