When I capture a snapshot with the Firefox extension, the snapshot looks fine in the thumbnail view, but when I select it for viewing, some images are missing.

Missing assets in the snapshot capture might be caused by the Content Blocking setting in the Firefox browser.

If Content Blocking is set to Custom, with Choose what to block set to Trackers / In all windows, this might cause images to go missing.

Change the Content Blocking settings and capture the snapshot again.

If the problem continues, contact Acoustic support.