I was just searching in on the DJI forum website for updates to posts on technical issues with the Matrice 200 series.  They have disappeared from the Products tab, but with some help from Google I found that they'd been moved to the "nature" section under the Works tab.  I'd therefore recommend that forum users search with Google rather that the Search box on the forum website.  

Hi, there Cori! Thank you for reaching out and we do apologize for the inconvenience. To provide a better user experience, we have divided the Forum menu bar in detail and increase the third level of the menu. Also, if you want to post or view some technical questions about the DJI Matrice Series you can just go into Products > Pro System. Should you have any concerns please let us know. Thank you for your kind and understanding. Have a good one!

During the forum 'optimization' older threads are being misplaced in the wrong section. (As user Cori already explained, a lot of the Matrice threads are in the 'Nature' section)

Simply said - move them back into their original place.
Thanks for understanding