I had made a similar topic a while ago regarding restoring a lost field group. The idea would be that by using the same field names, no data would be lost and the input could continue as it was done before.
I re-created the field group with all 5 fields ( I had the field names from the template output usage ) and indeed data is now showing up in edit screen.
The issue is that:
A) Fields don’t save anymore for new posts – I haven’t tried to edit an older one
B) A Google map field that I re-added seems to be extremely buggy with a location icon below “Search Address” and of course with search not working.
I have updated to the latest versions of ACF Pro and WordPress. I don’t know if it matters, but WPML is present and active ( although 2nd language is inactive at the moment )
Please keep in mind that ACF saves two entries in the database: the value and the reference. The value looks like this:
field_name : field value
While the reference looks like this:
_field_name : field_1234567890abc
Where ‘field_1234567890abc’ is the field key.
The issue you have mostly because the reference entries are not updated yet. You need to change the old field key with the new one. One method to do that is by using MySQL query. Please don’t forget to backup your site and database if you want to do that.