Hi,
I believe it does not have anything to do with the SSL. If the HTTPS does not raise any flags in browser, then yes, it means that SSL is working properly. But, if the response gives you blank page, then it means something does not work right. You should get the same answer when accessing it directly on http://127.0.0.1:8082/protocol-version (or http://127.0.0.1:41001/protocol-version in your case after your change) or on proxied URL.
This is response on my server:
~$ curl http://127.0.0.1:8082/protocol-version
{"version": 2}
It is hard to read from the screenshot, but I can see:
location /seafhttp {
rewrite s/seafhttp(.*) -1 break;
and that does not look like correct regular expression to me - hence I recommended to double check the documentation on that rewrite.