Fluent Forms Randomly Missing/Dropping Uploaded Files on Submission

Hi everyone,

I am facing a strange and critical issue with Fluent Forms Pro on my WordPress website, and I need expert advice or guidance if someone has encountered this before.

The Problem:
When users submit our multi-step visa application form and upload mandatory documents (like passports and PDFs), the files briefly hit the local temporary folder (/wp-content/uploads/fluentform/temp/), but some files randomly disappear or go missing right before the final form entry/submission is completed. As a result, the submission comes through, but the attached files show as "Not Found."

What We Have Checked & Ruled Out:
Server PHP Limits: High and optimized (upload_max_filesize = 1024M, memory_limit = 1024M, max_execution_time = 600).

Folder Permissions: The upload directories and permissions (755) are correct.

No External Cloud Storage: We are not using Google Drive or Dropbox integrations; files are meant to save directly to the local server.

Conflicting Code Snippets: All active WooCommerce and custom PHP/JS code snippets have been audited and verified; no syntax errors or restrictive hooks interfering with AJAX requests.

Hosting Environment: Other sites on the exact same server/cPanel account are functioning smoothly without issues.

If anyone has experienced this file-dropping behavior in Fluent Forms or knows what might be purging these temporary uploads during the AJAX request cycle, please let me know. Any suggestions or debugging tips would be greatly appreciated!

Thanks in advance.