Front page featured items and header problems

My site using Clean Business Pro (with a child theme) has been working ok since you helped me with the changes I needed to the masthead colours and position. However an error is occurring on the front page in which the IMAGES FOR THE FEATURED CONTENT AND THE HEADER IMAGE DO NOT SHOW. All other pages work fine. This error has occurred about 3 times over a two week period. If I go in the backend and open up the Customizer everything works fine again, but the error randomly appears again. Are you able to offer any advice? I will send you a screenshot by email. Thanks.