Mime Type errors for upload library

For troubleshooting, I'd try a single mimetype at a time. Upload a file with that mimetype and if it works, add the next one separated by a pipe and retry the upload with that new filetype. Keep going until it breaks.

I've never tried to put mimetypes directly in the $config['allowed_types'] and have always used a piped delimeter of extensions (pdf|jpg|gif), with the corresponding mimetypes in the /config/mimes.php config file. According to the docs, you should be able to use the mimetypes directly in the $config['allowed_types'], but I've never tried.