Hi @aedandev
I’m not sure if the update from composer will trigger the upgrade notice or not, but I believe it should be. You can also try the solution in this thread: http://support.advancedcustomfields.com/forums/topic/upgrade-from-4-to-5-pro-lost-all-fields/. Please don’t forget to backup your site and database first before modifying the file and upgrading the database.
Thanks!
