The new version of R2MLwiN includes a variety of bug fixes.
For details of new features and bug fixes go to: https://cran.r-project.org/web/packages/R2MLwiN/NEWS
For more details of known and fixed bugs visit: https://www.bristol.ac.uk/cmm/software/r2mlwin/r2mlwin-knownbugs.html
For a more detailed description of the changes, along with information on installation/upgrading see: https://www.bris.ac.uk/cmm/software/r2mlwin/