Happen to have a problem in your server that images is on https url and not being displayed properly?
I use this code whenever I got a problem in our server when using Woocommerce and Pretashop. It happens always on ecommerce sites only. It never happen in WordPress blog or site only. Mostly images are converted into https from http and because of that images are being display as question mark or a broken image.
To fix that copy and paste this code below in your htaccess
SetEnv HTTPS "on"
SetEnv HTTP_X_FORWARDED_PROTO "https"
SetEnv HTTPS "off"
SetEnv HTTP_X_FORWARDED_PROTO "http"
I hope this code can fix your problem too.