I have tried to log the bug, but am required to register with 2-step verification, and mysteriously fail to achieve that. If YOU succeed in registering, maybe you would do it ?
I was confronted with the same problem and decided at the time not to pursue it any further.
Personally, I'm not inclined to hand over my phone number to sites unnecessarily especially where it concerns a mere reporting of a bug in an open source application such as vlc.
There was a long running discussion on the subject recently which ended without a way of providing an alternative means of filing bug reports:
https://forum.videolan.org/viewtopic.ph ... 53#p522653
I would imagine that VLSub not working will crop up again in tbe not too distant future and the user will be willing to jump through all the hoops to report it.