If you are using WP Rocket and your gallery images no longer display, it might mean WP Rocket is interfering with Modula. This can be easily solved through that plugin’s settings.
WP Rocket has an option to exclude certain images from applying their lazyload to.
To exclude Modula’s images please go to your dashboard > Settings > WP Rocket > Media > Lazyload > Exclude image or iframes > and paste there: .modula-gallery .modula-items .modula-item img > save. This will fix it.