Can’t upload some .m4a files, can upload others

I’m having a strange problem with uploading .m4a files to my media library. I have two files, both of which are well below the upload size limit (and are approximately the same size: 4.5 MB). File A has a run time of five minutes, while File B has a run time of fourteen minutes. File A uploads fine, but File B gets a “Sorry, this file type is not permitted for security reasons.” The only way I can get the latter file to upload is by putting define(‘ALLOW_UNFILTERED_UPLOADS’, true); in my wp-config.php file. I’m not comfortable with this setting, due to security reasons, but I can’t figure out what limit is being crossed by File B, or how to adjust it.

Any insight into this issue is greatly appreciated.

• This topic was modified 6 years, 2 months ago by Jan Dembowski. Reason: Moved to Fixing WordPress, this is not an Everything else WordPress topic