MP3Tag not writing linefeed characters for m4a

I need to append line feed {LF} characters to my carriage returns {CR} in my M4A files so they display properly in my media player (as {CR}{LF}) but MP3Tag seems to scrub them automatically (a test on an MP3 worked fine) Is there a way to disable his behavior?

What have you tried in which field?
Did you have a look at the help on regular expressions?
(http://help.mp3tag.de/options_format.html#regexp)
especially \n and \r?

I have made an Action to "Replace with regular expression":

Field:
  UNSYNCEDLYRICS

Regular expression:
  [\r]+

Replace matches with:
  \r\n

I have also tested it with replacing \r's with 0's (worked OK) and just \n's (removed the \r's and left nothing behind).