This is a new issue that I haven't heard much on. I've got some steps that may help but not entirely sure if it will.
The first step being, make sure the launcher has fully downloaded the client and is not currently downloading any past information. If the game is fully downloaded, we will want to try clearing out the game cache and the Battle.net cache to make sure there isn’t anything that didn’t get updated/cleared with the patch.
Rebuild the Diablo III Cache 1. Navigate to /Applications/Diablo III/Data_D3/PC/MPQs and delete the Cache folder. 2. Then, navigate to Users/Shared/Battle.net/Agent and delete the Agent.db file. 3. Run the Diablo III Launcher and let the game update its files. 4. Press Play when you see Game is up to date