Hi davidfor and thank you for your help.
I finally found a solution out of desperation yesterday night.
The problem was the custom column, but not how you're thinking. I always had this column built with author+series working for creating collections on my kobo. The field is full of contents, I assure you. The problem was another. I always used the name "#auth_collez" to create collections but it was just the column name, its lookup name was simply collez. Yesterday night, really out of desperation, while I was trying to create a new column from scratch, I noticed the discrepance between colum_name and lookup and I tried and used just the lookup name #collez. And it worked!!!!
I don't know why the column_name always worked before. I don't know if the problem is the new firmware on my kobo or the new calibre version or a combination of both!
I'm just happy!
I'm detailing this for further reference. I'm also putting screenshots.
Thanks to everyone
