Today i run into an issue with a SugarCRM Instance, where i figured out, that some fields in where shown as NULL in my Studio.
To solve this, the first step is to have a look in your Database and select all from the Table called fields_meta_data. Look, if the fields are in the resulting output from the database. If not, you can create them again by running some INSERT INTO Statement against your Database.
In my case a enum ( Dropdown ) was missing in Studio, so i inserted the following:
insert into fields_meta_data VALUES ('sube_Verlaufsalutation_list_c', 'salutation_list_c', 'LBL_SALUTATION_LIST_C','NULL' ,'NULL', 'sube_Verlauf', 'enum', 100, 0, NULL, '2015-07-29 07:33:21', 0, 0, 0, 0, 1, true, 'salutation_list',NULL, NULL, NULL);
The first value is the Id, this must be the same as you named it by creation. Have a look at the Studio Fields View, there you can get all fields and the needed values, otherwise do an
on your database.
I hope this will help to fix some issues with your Sugar Instance.