Hi. Thank you for your reply!
I am the administrator of this machine. I do not see any issues on the server (though it is possible there is one that I am not aware of).
I have checked the Apache logs and have turned off SELinux and mod_security — the problem still appears when those things are off, and I see no other errors, apart from the 500 status code returned to the client.
Can you provide some hints as to what hosting configuration elements could be related to this CSV export problem? The server and site otherwise work great. ??
Thanks again for your help!