I was facing a similar problem. This might not fix for your problem, but it could help others that find this topic due to it’s title.
In order to get my prefered lay-out in the WP-admin, I put my fields in a group. I didn’t name the group since I used it entirely for aesthetic purposes. My fields didn’t save either, even though they were all named and labeled. Simply giving the group a name fixed the issue.
ACF Pro version 5.7.2
WP version 4.9.9
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users