I was finally able to solve this problem.
After migrating from 3.1.x → 3.2.x → 3.3.010
Something happened in the middle that the submission table in the column “locale” showed with NULL values.
I changed the values for “es_ES” and in some articles and I did tests and voilà! no more mistakes!.
Then it proceeded to change all the values with their corresponding language.
Problem solved.