Basically, you are unable to advertise that you are looking for seeders without your incoming port open. This problem would mean that you need to find a more active torrent, since none of the seeders are able to see you or stay connected. The other option would be to forward that port.
You should be torrenting behind a VPN, unless your country has no laws against it. My VPN, mullvad, no longer forwards ports, probably for legal reasons. The port would have to be forwarded for the requests to make their way through the VPN to you. I do not have an answer for what VPN would enable this behavior.
In some cases, torrents may also be honey traps that never complete in an attempt to find out who is sharing illegal content. These only ever seed to 99% and you will see a handful of other users with the same completion, never finishing. Again, in those cases, it is best to move along.
Basically, you are unable to advertise that you are looking for seeders without your incoming port open. This problem would mean that you need to find a more active torrent, since none of the seeders are able to see you or stay connected. The other option would be to forward that port.
You should be torrenting behind a VPN, unless your country has no laws against it. My VPN, mullvad, no longer forwards ports, probably for legal reasons. The port would have to be forwarded for the requests to make their way through the VPN to you. I do not have an answer for what VPN would enable this behavior.
In some cases, torrents may also be honey traps that never complete in an attempt to find out who is sharing illegal content. These only ever seed to 99% and you will see a handful of other users with the same completion, never finishing. Again, in those cases, it is best to move along.