I’ve finally figured it out!!! Long story short, it turns out that a dev-only Flipper network interceptor (and thus also the staging versions of app I was shipping out to android testers) messes specifically with these type of single file uploads. See this comment in this GitHub issue here:
As soon as I comment out that line in Flipper interceptor, uploads are working beautifully and as expected with Android devices!!!
Thanks for all your diligence and effort here.
Really an annoying solution in the end, but that’s usually how stuff like this turns out
Hope this helps anybody who may find it or run into it in the future.
