Symptom
Images stay blank, appear at a tiny size, or overlap. Two lazy loaders are fighting over the same image.
Cause
Another lazy loading feature, from your theme, an optimization plugin or a CDN, rewrites the same images that Visual Portfolio has already rewritten.
Fix
Run one lazy loader, not two. Either turn the other one off for gallery images, or open Visual Portfolio → Settings → Images and set Lazy Loading to Disabled.
The plugin already turns its own lazy loading off when it detects EWWW Image Optimizer, Lazy Loader, SiteGround Optimizer, Avada or Enfold, and it cooperates with Jetpack, a3 Lazy Load, Imagify, Divi and WP Rocket.
To leave single images out, add the no-lazy class to them, or list them in Lazy Loading Excludes on the same settings screen.
Jetpack in Safari needs its own fix; see Jetpack images lazy loading conflict with masonry.