Are we 100% sure the watched words regular expression site setting was flipped to true?
If that is at its default (false) then watched words wouldn’t be regular expressions at all, but also it wouldn’t be matching as it is in your screenshot … so I’m not sure. @neil?
I also can’t repro this on my instance of discourse @awesomerobot :
- turn on
watched words regular expression - enter
\bass\bin censored section - I see correct word boundary only censoring