Arma 3 has recieved an update today with the release of the Tanks DLC. But as with every update I need to do some testing to make sure everything behaves as I expect before we update. I hope to have us update by the end of the month but until future notice can you please make sure you are on the legacy branch.
To do this head to your Steam Library, right click on Arma 3 and select properties. Swap to the "Beta" tab and enter the code Arma3Legacy180, hit check code and select legacy from the drop down menu. If you have any issues please let me know.