This is currently an active known issue that our QA and Developers are investigation for resolution. At this time we do not have any workarounds. If you are working on a major map project yourself you may consider using a windows System or Windows boot camp only if you have this easily available too you till the issue can be resolved or when just working with ramps.
Customer Service does not have an ETA on when this will be resolved but our developers do have this listed as a known issue which our QA team is actively investigating. I would expect it to be resolved in the near future given the impact this would have with creating maps on Mac systems.