If you search the forum, you’ll find plenty of topics regarding that bug. I haven’t noticed any lately, so hopefully it’s gone for good, or at least not active currently, so you probably don’t have to worry. I just mentioned it as it’s one of the reasons I started taking and saving screenshots of all deliveries, and for screenshot clutter on my pc.
It happened to many people for a while, and I think there were two or three iterations. Basically, people delivered, attaching their files, but the files didn’t show up on customer side, which led to “empty delivery” warnings for some sellers. So, to be able to prove that you actually did attach the file/s, it was a good idea to take screenshots that you could present to support, in case your deliveries would be flagged, or reported by the buyer as “empty delivery”, as empty deliveries are obviously not allowed.