Missing data within the dataset

I have been collecting some data with kobo toolbox via link. However, my dashboard is indicating I have 10 missing data. But all my questions are mandatory. If you don’t fill then you can’t submit. So what the cause for the missing data?

Below is a link to my form

if you skip a question (relevant specification), the case will have "missing’ (empty) fields, even with all questions = required. required is only getting active IF the question is relevant.
Kind regards