If the file is too large you may be running into nginx's clientmaxbody_size which if exceed should return a 413 error, though some browsers don't support actually reporting that error correctly.

You would want to increase this to a larger limit or set it to 0 in which case there will be no limits.

http {
    # [...]
    client_max_body_size 100m;
    # [...]
}

If that doesn't fix it you will want to tail your error logs for both nginx and meteor to see if you are getting something more specific and then provide that in your question as there maybe other factors at play.

Great answer by @moisey!

Another thing to point out is that, this setting of "clientmaxbody_size" does not come included by default in the http section of the nginx.conf file. You have to add it manually in order to increase the setting to whatever number you need.