Hi @cjp160 , I'm trying to debug the issue using the project that you posted on Dec 17 but the HTTP server is unreachable (even changing to HTTPS). Could you please send me an updated version of the project to run in-depth tests?

Hi @cjp160 after further investigation we can confirm you that this is an Apple bug that affects multipart data with a HTTPS connection to a HTTP2 server. We'll soon release an improved version but there is really nothing we can do until Apple will fix that bug.
Can you disable HTTP2 protocol from your server? Alternately, can you use HTTP?