Tamper Monkey 4.5, Google Chrome 64, can't find cause for this on my end.
Replicated on Firefox 58.0.2, webextension, issue began within the last hour or so.
Tampermonkey 4.5.5660
Firefox 58.0.2
Iridium is not doing it's job for me either suddenly.
Can confirm, will see what YouTube changed again that caused this to stop working.
I am considering dropping the userscript version so that I have considerably more freedom to preemptively account for these constant changes YouTube does, something that is currently not feasible with the userscript version, as well as other limitations associated with the userscript version.
It's nice to have it as an option for situations where their is no extension.. But I don't use the script myself as I find they can load slower on older systems.
Most helpful comment
I am considering dropping the userscript version so that I have considerably more freedom to preemptively account for these constant changes YouTube does, something that is currently not feasible with the userscript version, as well as other limitations associated with the userscript version.