There is an issue that has been reported to Canvas with regards to images not appearing when using New Quizzes and Respondus LockDown Browser. The issue seems to occur when a Classic Quiz is migrated to New Quizzes. A similar issue occurs when a brand new New Quizzes exam is created, depending on how the image was embedded.
A workaround has been found to avoid re-embedding all images that might be helpful to users. The first step is to group a single Classic Quiz and banks that you wish to migrate into a New Quiz bank. After grouping, download the QTI file as a New Quiz bank, then create a New Quiz based on the QTI file by importing the downloaded QTI file as a New Quiz. This should let the images load correctly when your students use Lockdown Browser.
The following links may be helpful when completing this workaround.