I am experiencing the same thing. Using Moodle 4.0+, but has been an issue for a while. I uploaded questions in Aiken format for a programming course, and it converted symbols to HTML format symbols (ie... '&' uploaded to &). So, I am working on cleaning up the questions, going one by one through the preview. If it is wrong, it is nice to be able to update the question right there, by selecting the 'edit' link. This works good! The only issue is the question in the preview does not update (it does not update for the student either). If I delete the student attempt, and they retake it, then it is fine. I'm okay with that, but it would be helpful if I could at least delete the teacher preview attempt. Since it is holding on to the previous preview, I have no idea if the question has actually been updated or not, unless I go back in to the edit window.
Not sure if there is a way to add a 'delete previous preview' type button, or a way to clear or refresh the past preview. Would be even better if the students side of questions would update as well; without the need to totally delete their entire attempt and force them to start fresh.
Thank you for your time, support, and input!