Worked with the server admin on this issue. In php.ini we have this set:
; Whether to allow the treatment of URLs (like https:// or ftp://) as files.
; https://www.php.net/manual/en/filesystem.configuration.php#ini.allow-url-fopen
allow_url_fopen = On
With this setting enabled, and even re-starting the server to make sure the init was caught correctly, the issue persists. This problem is occurring in the latest Chrome browser. The server is running PHP 5.3.3.
Is there anything else we can try?