Thank you for reaching out to Okta Support! As a general behavior, the security image will not be shown on the login page once the username field has been filled if: - the cache has been cleared for the browser since the last login; - an incognito/private window is used for logging in. For the above mentioned cases, a prompt containing the following will be displayed: "This is the first time you are connecting to domain.okta.com/domain.oktapreview.com from this browser" As per the description mentioned in the question, the behavior seems to be different. We would recommend testing it on different browsers/machines and in case further assistance is required, please open a support case and we will be glad to assist you.
Kind regards, Cristian Mondiru Technical Support Engineer