Tested under Moodle 3.8.6, plugin version 3.9.0 (Build - 2020062300).
If a student uses a period, no problem, his answer is accepted and recorded. In the example below, three students that used a comma as a delimiter see that they answered the questionnaire, but those answers are NOT visible from the teacher's perspective, only three other responses using periods are shown:
I've tried changing the course language to see if this would change anything, no dice.
How can I fix this?