Missing Photo Attachments in Mandatory Image Question

We are facing an issue with one of our Kobo forms. The photo question in the form is set as mandatory and cannot be skipped. However, after exporting the data to Excel, we found that around 25 image attachments are missing.

The records themselves exist in the dataset, but the image files are not available in the attachments/exported data.

Could you please advise on:

The possible reason for this issue
Whether the missing images can still be recovered from the server
Any recommended steps to prevent this issue in future submissions

Your support would be highly appreciated.

Welcome back to the community, @iyd! Could you let us know on how you collected your data? I mean did you use the Collect Android App or did you use Enketo (web-form) to collect your images?