this is not a bug nor related to the fact it's an unreleased version. It only show something new because of the new workflow enabled by the DCBuddy, it's only a upcoming way of using DiveLog and MacDive together.
To be complete, and to take Greg's word'd on this topic (I also asked him the question):
I though MacDive was also calculating average depth at needs and not only once on import. Obviously notDive Log always calculates the average depth for the dive at the time it calculates the SAC rate (our while displaying the profile). It never stores the average depth except in the case that there is no profile set (in that case Dive Log gives you the option manually set the average depth). So in a sense, there is nothing to “send” to MacDive.
You might get in touch together to check this (non urgent) topic
Matt