When using the Bootstrap theme,
If after answering some types of questions (many questions types using a textarea for answer seems affected but I didn't tested all of them, I tested shortanswer and numerical and they are affected) you click on "Submit all and finish", and if you review your attempt, all your responses are hidden. The feedback image (green check or red cross) is displayed but the response itself is not.
Inspecting the element this seems related to

.que .correct:empty {

    display: none;

}

and the same with incorrect:empty, but not really sure as my knowledge of Moodle styles is pretty limited
I attach 2 screenshots of a shortanswer question, one after clicking on the "Verify" button where the "Bootstrap" answer is visible and one of the same question after clicking on 3submit all and finish" where it is invisible.
the problem can be tested both during previewing a question and when reviewing a quiz.
I have set components of this issue as both Thme and Questions but I am nearly sure this is a Bootstrap theme problem.