The mechanics can be endless to account for this. Wolves didn't submit an action, wolves submitted an action but didn't format it properly, other reasons kills can fail. Maybe kills only have a percent chance of working. I know this is supposed to be basics, but it's Lawpy. This pack might be different, but unless Visc can self protect multiple nights in a row, and wolves have tested this theory, I don't know how she can still be alive right now if kills are straightforward (submit and if no mechanics block it, player dies).
It's game breaking if Visc can self protect multiple nights in a row. If I were wolf pack, after first failed kill due to protector, I'm submitting to kill the protector every single night barring nights I have reason to think the protector is self-protecting. I become obsessed with taking out the protector and no more no kill nights. Why have they left her and just focused elsewhere so many nights? That seems risky.