Hi again,
aha as I was suspecting, the problem, was mine after all!
After completed a migration from sqlite from mysql, the sql script didn’t recreated the tables with the auto-increment flags on the IDs, so there was not possible to insert new values in the wp_options, where your option called ‘ai_writing_assistant__api-key’ was being stored correctly.
Don’t bother more, sorry fot wasting your time! Alas…