From what I understand there is a bug in the date and time picker, more than likely caused by changes in the version of jquery used by WP. There was a similar issue here https://support.advancedcustomfields.com/forums/topic/meta_query-orderby-overwritten-by-publish-date/. If you post in that topic maybe that person can tell you what he’s doing to fix his problem or you should try contacting the author of the date and time picker https://wordpress.org/support/plugin/acf-field-date-time-picker
