I have over 100 hand coded gcode files that ran perfectly on a Mk1 controller with 2.10.1412.1501 on WindowsNT. I recently updated to 2.10.1807.2601. After the update all my existing files that had while/endwhile constructs stopped execution (actual and simulated) after the first encountered endwhile statement. All existing files that did not have while/endwhile constructs continued to run perfectly after the update.

Any suggestions?
Is a download of 2.10.1412.1501 available to revert my update?