The import log reports : Could not add non-preferred label to ca_objects: Name must be at least 1 characters
Can import or modify a nonpreferred_labels field with length >= 1 character.
If lenth = 0 :
The record is created well, but import process logs the above error.
The nonfreferred label remains not modified after next Import processes.
The record then shows several occurences of Alternate title, in same quantity as successive imports of not empty values (with several duplicates).
Empty content in import files are ignored (should be erased !)
Tested with TabDelimited and XLSX data import file.
PHP 7.2, MySQL 5.3 All privileges granted on SQL base
app.conf : unique ID for objects and entities set to ON
mapping : no option, no refinery, mapping field by field.