Just wanted to let people know I have stumbled across a bug in the row splitter (Manipulation->Row->Filter->Row Splitter) in release 3.4.1.
The regular expression option is non functional. (See the attached image of the configuration dialog for settings). No matter what kind of regular expression you put in, no filtering takes place. As you can see the filter I wanted to use was nothing tricky. I tried single and double quotes, using a single string (no 'or' operator) and it absolutely refused to filter any data. When I uncheck the regular expression option, it performs as you would expect. string matches, wildcards, etc. all work. But check the regular expression box and it stops filtering altogether. No error messages or other misbehavior, it just doesn't filter anything.
Easy work around, just use plain string matches, and avoid the regular expression option.
No response needed, just wanted to let people know.
BTW, I am running Windows 10 Enterprise OS if that matters.