Hi I've seen this problem before and seem to have it myself.

I have a number of torrents seeding from this tracker, but all have 0.0 ratio.
I have checked and some of them DO HAVE LEECHERS, meaning I should be uploading.
I am able to upload from other private trackers and see my ratio increase.
I figured if it was a port issue I wouldn't be able to upload from other trackers.

I'm using qBittorrent 3.3.7,
any help would be greatly appreciated.

Versions of this question has been asked many times and the answer still remains that the distance between two users, the circumstances like connectivity, configuration of connection, routers, firewalls etc etc, make it impossible for anyone without full access to your situation to know the exact reason you are not uploading. It can just as well be the downloader(s) that cant connect to you because of some misconfig on their side as it could be your own connection. Important is to understand that uploading on a torrent with hundreds of leechers is not same as when there are only a few. In a swarm of hundreds some are sure to be able to connect to you and the swarm itself creates connectivity.

For the record.... we made some tests and it looks like it does work, even if in this case the speeds where slow, with a little patience and an update of torrent client to utorrent things started moving.

I also wanted to remind you that in many cases when you see that a torrent has leechers but you dont seem to upload anything when you are seeding the case is that the leechers have only selected to download a few of the files in the torrent and not all, so even if they have completed their part of the download, they show as uncompleded (leechers). This can often happen on some older multi file torrents like packs or similar.