Always same answer for multiple choice quiz

There is a series of serious bugs in the multiple choice question.
1. In the feedback part, if I write, for instance, "ok" for the right answer and "wrong" for the wrong answer. The system writes "ok" in any case.
2. Every time I try and modify the question, the system introduces one or more new choices that I cannot delete.
3. The most important bug of them all: No matter what I write in the alternative answers, the systems changes all the answers I have carefully chosen and writes only the single digit "1" for all the choices.

Needless to say that the multiple choice tool is unusable as it is.

In the jpg image you can see how the quiz looks like for a student.