Error when renaming quiz

Hi,
First of all, congratulations for this great plugin!

I have an issue when renaming quiz, though.
When I clik on Edit name and Edit, there’s a success message:

“Success! The name of your quiz or survey has been updated successfully.”

But just below there’s this error message:

“Error! Please go to the quizzes page and click on the Edit link from the quiz you wish to edit.”

And quiz name looks OK just after rename, but if I go back to the quiz list or if I refresh page, quiz name is back to previous name.

Renaming was OK a few weeks ago, so I think the issue appeared in a recent update (or maybe WP update).

Tested with WP 5.3.1 and QSM 6.3.6 and no other plugin activated.

Thx for investigating!
Yan