Dynamic Data Attachment: Multiple Selects not Updating

I was using the dynamic data attachments functionality and trying to retrieve data from a parent project.
The screenshots of the forms are attached below.
Though, the form successfully links data for single_select questions, for select_multiple we don’t see any output.
Does anyone have some insight as to why it’s not working?
Thank you.

Welcome to the community, @prabhmeetkaur! Would you mind using the sample XLSForm as shared in the support article to see if that too should have issues? If not, maybe you will need to go through the sample file shared in the article: