ASP.NET Core React Application returning 400 with no message on GET

Question

My application was working fine, and then the next day I ran it (dotnet run) and it started returning 400 for all requests, with no message. I can reproduce the issue on various machines; however, some of my coworkers cannot.

I am unable to get my code to break on the exception - all break points seem to lead to a successful response. I've tried changing my debug level and configuring logging in Kestrel using:

.ConfigureLogging((hostingContext, logging) =>
                {
                    logging.AddConsole();
                    logging.AddDebug();
                    logging.AddEventSourceLogger();
                })

I also tried adding some middleware per this post: https://exceptionnotfound.net/using-middleware-to-log-requests-and-responses-in-asp-net-core/

This did not give me anything more than it is returning a 400.

How can I get more about the error so that I understand what is causing the underlying 400?

What I'm seeing:

Microsoft.AspNetCore.Hosting.Internal.WebHost:Information: Request starting HTTP/1.1 GET [my url]
Microsoft.AspNetCore.Hosting.Internal.WebHost:Information: Request finished in 1044.473ms 400 

Some obvious culprits that I have ruled out:

• Authentication is occurring successfully.
• No changes ran on my machine in the mean time aside from an anti-virus definition update.
• I did run an npm install, but my coworkers did as well so we should be on the same versions of everything.
• My git status is clean so there shouldn't be any hidden changes in my local repo, and I tried it on two other clean machines.