Edit Order Removing "main_Pair" Information

I was testing adding additional products (v4.6.2) to an existing order from the admin section and when I did, any products in that order with an option for custom file upload had all their main_pair data removed. Meaning the product thumbnail and all data associated with it. This only happened to products with that option. The others remained as they were before editing the cart. The custom files array was unaffected as well for the products having thumbnails removed.

ALL product thumbnails are still visible on the admin page:


But if I try to access the same order with /api/orders/1234 that main_pair data is missing.

Any ideas as to why?

I would report that to bugtracker. Be sure to include a way for them to reproduce since it's a rather unique case.