Hi Jmillner1,
Thank you for reaching out. It is true that at the moment, if you have questions with images attached to item banks, it's likely that there will be issues sharing those questions to other courses, since the ID we're looking at is still that old image. A brief explanation of what is going on is that the link we see for the image still has the original course in the item bank, and Item banks exist on their own, which makes the image link not update between courses. I believe we are still looking into this as well to see how best to resolve it.
I would recommend reaching out to Canvas support for an issue like this, as they can take a look and see what exactly is the best option. A few general suggestions I've seen in the past include the following.
1. Adjusting the file visibility to "public", so that anyone can see the image. This bypasses restrictions we have that makes the file require you have access to the course before you can view it, so while it doesn't work for all cases, it does make it so that the image will work for any course/quiz despite being linked in an item bank.
2. exporting the quiz content and not re-adding it to an item bank. You should be able to import content directly into a quiz, and having the teachers do this should make it so that the images are solely on the quiz, and not in an item bank. When the quiz is then brought over to a new course via a course copy, the links will update properly.