I already posted this problem/question on Stack Overflow, but I haven't received any helpful response so far. That's why I chose to pose the same question here.
Link to Stack Overflow question
To summarize my issue: when trying to send a POST request with size greater than 64 KB to our REST web service (ASP.NET Core 2.0, on dev and test machine), it never completes, no matter the content. Not even the respective controller methods are called and nothing's being written to the logs (with the exception of the trace log. See Stack Overflow question). However, when I run the sample app and web service from the tutorial mentioned in the Stack Overflow question linked above, uploading images bigger than 64 KB works flawlessly, even when running a copy of said example web service with settings changed to match those of our actual web service in development (such as check arithmetic overflow/underflow, target platform x86, full .Net Framework, manually loading appsettings.json, using custom error handling etc.)
I've also tried several request size related web.config settings which didn't help either.
Does anyone have an idea what could be the cause of this limitation?