So it seems that we've made some solid strides for the 'unable to download' issue and have a possible fix to test. The 'unable to publish' is still being researched and I've made sure to forward the reports people have been making. It's our goal to recreate the issue in house and have the logs to study to find a fix.
So from our perspective, both being unable to publish, and being unable to download maps has not been fixed in the live environment.
From an experiment I ran it seems related to the player's geographical area. People who are logging in from places like Australia and South Korea have no issues downloading updated maps on the US servers almost immediately after they are published. However people connected in or near the United States of America are unable to download the maps directly after update. It also appears that the issue self-resolves after a period of time.
I tested quite considerably 2 weeks ago. 7 players who could download my updated map all came from the South Korean/Australian area. All the people I asked who could not download the map reported they live in or near the USA.
Due to the regional nature and time related self-fix it sounds like a typical data consistency problem. If some form of localized distribution for data (map/mod files) is used to reduce long distance traffic it is possible that the US server is taking a long time to synchronize with other servers around the world.
This could be the result of it being under unusually high strain from the WoW expansion but I would have imagined the results of that having faded by now. That said I did not have so much trouble with my last update. I published it off-peek however (US night time/early morning) so the servers could have been under less strain so performed better.