This is somewhat related to my earlier post from December (thanks again for the quick response!). The problem I was having back then is resolved, but I notice there is a lingering issue related to removing files.
When a user adds a file, then removes it, and then changes their mind and tries to add it back, they are unable to. It does not show up visually, and it also doesn't upload if the button is clicked (it just sends the default 44 bytes like any empty upload).
I did some debugging, but didn't get very far because I couldn't get any breakpoints to hit when re-uploading the file. In RadzenUpload.razor.cs OnInputChange wasn't hitting, and in Radzen.Blazor.js uploadInputChange wasn't hitting either.