I am experiencing this as well. I cannot make changes to an existing group.
TypeError: Cannot convert undefined or null to object
at Function.entries (<anonymous>)
at acf.Model.addProLocations (acf-field-group.min.js?ver=6.2.0:1:25790)
at acf.Model.initialize (acf-field-group.min.js?ver=6.2.0:1:25516)
at acf.Model.e (acf.min.js?ver=6.2.0:1:3259)
at o (acf.min.js?ver=6.2.0:1:1405)
at Object.doAction (acf.min.js?ver=6.2.0:1:575)
at n.doAction (acf.min.js?ver=6.2.0:1:19006)
at HTMLDocument.<anonymous> (acf.min.js?ver=6.2.0:1:28275)
at e (load-scripts.php?c=0&load%5Bchunk_0%5D=jquery-core,jquery-migrate,utils,wp-polyfill-inert,regenerator-runtime,wp-polyfill,wp-hooks&ver=6.2.2:2:30158)
at t (load-scripts.php?c=0&load%5Bchunk_0%5D=jquery-core,jquery-migrate,utils,wp-polyfill-inert,regenerator-runtime,wp-polyfill,wp-hooks&ver=6.2.2:2:30460)
