We are using the Select Missing words question, in M4.1 and further and encounter different behaviour in the Quiz Navigation.

This does not seem to be limited to the Select Missing Word question, we also encounter theissue with Multi Choice with 1 answer question. 

What is the issue

When a student submit the questions, on there summary page the see which questions they have answered right,wrong or partly right. 

The Quiz navigation should show the correct colours with this response, but as you can see in the attached screenshot. We see alot of 'grey' coloured questions in the Quiz navigation. 

What did we notice

When we check the inspect tool we noticed that there is a variation in classes being used. And for some reason, in most of the cases of Select Missing Word Question we get the class 'qnbutton complete free btn thispage' instead of the 'qnbutton correct...' or 'qnbutton incorrect'. or the one for partly correct (question 19 in the screenshot) 

It is not in all cases , as you can see question 8 and 9 it does show the correct colour even though it are Select Missing Words. 

I have not found the reason in this inconsistent behavior.