.cs & .ts files not supported in file search despite documentation stating text/x-csharp & typescript is supported

I’m encountering an issue when I try to upload a .cs or .ts file to the OpenAI Playground. According to the file search documentation, .cs and .ts files are supported with the MIME type text/x-csharp/typescript. However, when I actually attempt to upload a .cs or .ts file, the Playground refuses to accept it and shows an error :

Interestingly, my Windows file browser does allow me to select .cs and .ts files (and the “File type” dropdown lists *.cs, *.ts as supported), so it seems like there’s a mismatch between what’s documented or shown in the file browser vs. what the Playground actually allows.
This image shows a file selection dialog box with options to open files of specific types. (Captioned by AI)

Could you please let me know if there’s a known bug or workaround for this issue? Thanks in advance!