Strange mysql behaviour with fulltext search on id 1

I have a table (INNODB db) with thousands of records and some columns are fulltext indexed. I use fulltext in boolean mode and it works very well, except for the row with id 1. It always show me that relevance is 0 even if searched word/s exists inside indexed columns, and on other rows that word is regularly found. I’ve already checked up stop words but that’s not the problem. It’s like fulltext search is blind on row with id 1.
Any suggestions?