Cannot disable bt.use_dns_tracker_prefs

[SL9]

Hello,

I have disabled bt.use_dns_tracker_prefs in advanced settings but for unknown reason, it has no effect on some trackers. For example: 

http://tracker.opentrackr.org:1337/announce

As soon as I added this address, it is automatically converted into udp. I cannot use udp tracker due to regional law reasons.

According to opentrackr's official twitter, http requests are usable and I can use it in other torrent clients.

For some other trackers like http://explodie.org:6969/announce it won't auto-convert to udp. (Which it will if bt.use_dns_tracker_prefs is enabled.)

Is there anything I overlooked?

Thanks!