Torrent Address Detection NOT working?

[j take 1]

I use BitTorrent.  When I add the magnet link and start the download, I get  "connection closed by peer" in the trackers panel, and my IP address doesn't appear in the Torrent Address detection section.
I didn't used to get this result before (last year?) I hadn't used Bittorrent for a while.
What am I doing wrong? Does it by chance have something to do with enabling ipv6?

[OpenSourcerer 1435]

The BitTorrent client, or some other BitTorrent client like Transmission, qBittorrent, Deluge, etc.?
 

On 1/11/2020 at 7:40 PM, j take said:

What am I doing wrong? Does it by chance have something to do with enabling ipv6?

Could be. qBittorrent for example currently has a bug: If you enable IPv6 and have bound qBittorrent explicitly to any interface, the client cannot connect anywhere, neither to trackers nor to peers. Maybe other clients also have difficulties with IPv6. Can you try disabling it?

[j take 1]

Thanks for the reply, Giganerd.

I am using The BitTorrent client. Torrent Address Detection used to work fine when I last used BitTorrent about 6 months ago. The BitTorrent client on my Mac wasn't changed since then.
I have no problems downloading any torrents using this BitTorrent. Only, when I start the Address Detection magnet I get "Connection closed by peer" for the tracker status. 
What does that mean?  (IPv6 is Off in my network setting, and ipleak.net says "IPv6 test not reachable".)

I'm using BitTorrent version 7.4.3. (On an aside, the client says 7.8.0 is available. But their website has No mention of it!)

I tried the Transmission client. The Address Detection works fine!  Maybe now I'll try updating BitTorrent to 7.8.0. - or uTorrent.