Postive Lookbehind (RegEx) does not work in flow designer

When a string is passed in via the flow action's inputs, and then used with JS Regex Object, it does not work.

Observe the following piece of code:

var stringToMatch = "asdf\r\nasd\r\nfasd\r\nf\r\nRequested User:Jason Smith (AD\\1122334455884444)jason.smith@test.com\r\nd\r\ndddddd";
var pattern1 = "(?<=\Requested User:).*";
var regEx1 = new RegExp(pattern1, 'j');
var stringfound1 = (regEx1.test(stringToMatch)) ? regEx1.exec(stringToMatch).toString() : '';
gs.info(stringfound1);

if the stringToMatch & pattern1 variables are defined from the flow action's input, and the regex code is inside a script step, the regex will fail to match the pattern and will not return anything

STEPS TO REPRODUCE:

1. Create a flow action with two string inputs, once for the string and another for the regex pattern
2. In the action create a script step where the above code is ran to match a pattern and have the script step return the match
   
3. Test and add the following as inputs
   

string to search:

line 1
line 2
Requested User:Jason Smith (AD\1122334455884444)jason.smith@test.com
line 4

Regex pattern used:

(?<=\Requested User:).*

4. Run test
5. Observe in the context in the script test, there are no values in the runtime value outputs

\r in the regex pattern is causing conflict when translated to java

you can use the following pattern instead:

(?<=Requested User:).*