Fix WhatsApp Bulk Image Sending

My WhatsApp Business API script sends text in bulk without a hitch, but every JPEG attachment stalls. The platform answers with error codes (I’ll share the full JSON responses) even though the files are well below size limits and use standard resolution, so the problem clearly sits in the media-handling flow, not the images themselves.

I need you to inspect the current code base, trace why media messages fail in bulk mode, implement the required adjustments—be that tweaking the upload endpoint, altering headers, batching logic, MIME settings, or anything else you uncover—and verify success with a real-world test broadcast.

Deliverables
• Updated source code or patch that lets a bulk send deliver JPEGs alongside text without errors
• Clear notes on the change(s) made and why they work
• Short walkthrough or screen share proving a successful bulk push (image preview visible on recipient devices)

If you have prior experience with the WhatsApp Business API or similar messaging gateways, you should find this a quick win.