You can not set a category to contains thumbs and expect it to not be uploaded to
In Reviewpost if a category is set to no thumbs it is not even shown on the upload list so you need to set it as you had but check permissions and then since I can not replicate this on several installs I would suggest making sure you upload all the new files. Behavior like this is usually created by having a mix of files on the system. FTP programs are real good sometimes at not overrighting old files.