This issue has be fixed for me since the June hotfix

This has happened for myself as well a group of people I play arma with, It started around the time of the Karts DLC release, of which not all of us own the DLC. Also in the first few days of the DLC release some of us where still able to view the slots when Local Hosting on the internet. I have done a steam verify on the game cache as well as a full re-install of arma 3 to try solve the issue, to no success. Hosting a mission in New > LAN the slots will be visible, but hosting a mission in New > Internet all slots and mission information will not show. This happens for both custom made missions as well as BI created missions.