Hi Richard,it's a known issue (https://github.com/wspr/fontspec/issues/closed#issue/79 and https://github.com/wspr/fontspec/issues/#issue/65), but we'll have to wait for either Will or Khaled to come up with an adequate fix for the next release.
- Mike "Pomax" Kamermans nihongoresources.com -------------------------------------------------- Subscriptions, Archive, and List information, etc.: http://tug.org/mailman/listinfo/xetex
