[LH3668] Compile RegExp replacement not working

Re getting the compiler to double space some text, no amount of substituting a single occurrences of \n, \r, \n\r or \r\n with a double occurrence results in a double spaced markdown file being produced. No error, but the the resultant file has line breaks as per the source text.

E.g adding a replacement of \n with \n\n has no effect.