Submissions missing in ODK Central

1. What is the issue? Please be detailed.
One of the user has reported an issue that on download submissions, there is a response with the ID uuid:xyz which is present in the main response sheet, but the corresponding information is not available in the sheet containing the response for grouped questions.

2. What steps can we take to reproduce this issue?
We analyzed and found that there is an option (Minus sign(-) in repeat) available in the survey form to delete the group of responses.
if user delete all repeated group responses using minus(-) sign displayed on the right of the repeat group questions and submit the survey then submitted survey information will be available in main response sheet only.

3. What have you tried to fix the issue?
We are looking a way by which deletion of at least single repeated group questions can be restricted. Kindly suggest.

4. Upload any forms or screenshots you can share publicly below.