I found this in the mysql.log

Script: /home/dbs/ubbthreads/frame/scripts/filemanager.inc.php - Line: 285
UPDATE ubbt_FILES
SET FILE_NAME = '5.jpg',
FILE_ORIGINAL_NAME = 'yellowedge.jpg' ,
FILE_WIDTH = 0 ,
FILE_HEIGHT = 0 ,
FILE_SIZE = '' ,
FILE_SHA1 = ''
WHERE FILE_ID = 5
- Incorrect integer value: '' for column 'FILE_SIZE' at row 1

For some reason the file size is unset.