Lowercase abbreviations such as 'Bout, 'Cause, 'Em, etc

I want an action to lowercase abbreviations such as 'Bout, 'Cause, 'Em, etc. to 'bout, 'cause, 'em, etc. I thought I had it solved but now it doesn't work for some reason, perhaps because \b doesn't work in all files(?).


Could you show us the cases where it does not work?
MP3tag has a preview function in Converter>Tag-Tag where you can test scripting functions like $regexp().

If all that does not help, you could try alternatively an action of the type "Format value" or the already mentioned converter Tga-Tag and the scripting function $replace() in which you replace the upper case words with lower case ones.