Issues importing TestGen questions with graphics into Canvas

[yoffema]

I've had no problem importing text-only quizzes generated using TestGen into Canvas.   I simply export the quiz from TestGen as a QTI zip file, and then import it into Canvas from the Settings section (specifying that it's QTI zip).  Detailed directions available here:

https://community.canvaslms.com/t5/Question-Forum/Is-TestGen-Compatible-with-Canvas/td-p/136639

However, if any of the questions contains a graphic, then the graphic doesn't import.  Specifically, it's as seen below. Is there a way to fix this?

[Possibly related, from 6 years ago, involving files imported from a different publisher:

https://community.canvaslms.com/t5/Question-Forum/Images-not-visible-in-QTI-imports/m-p/67597#M9643 ]

I'm using TestGen v. 7.7 (64-bit) on Mac OS 10.13.6.

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Suppose the TestGen question contains a line drawing like this:

Here's what's shown after I import into Canvas:

Here are the error messages Canvas gives me: 

• The file "x-webct-vista-v0/f118g8_r__r.png" did not exist in the content package and could not be imported.
• Missing links found in imported content - Assessment Question question_text