Random tag question not appear in preview

When setting randon questions by tag in a quiz and clicking on the magnifying icon for previewing the question - the previewed question that appears is not from the tag that was supposed to be.

The questions shows in the quiz as they suppose to (from their tags)  but when the teacher wants to  click on the magnifying icon (see image) for previewing the question (for himself) in the "edit quiz" page - the previewed question that appears is not from the tag that was supposed to be.

To reproduce

• create some questions, some of them with the "mytag" tag and some of them without the "mytag" tag.
• create a a quiz and add a random question with "Tags" "mytag"
• On the quiz edit page click on the magnifying glass for the random question, you will see that you can get either a question with the "mytag" tag or a question without the "mytag" tag (repeat this several times if it appear to work and you will see it doesn't) .