Still happening. saw people on top of the bridge and skyscrapers on the Manhattan map in Breakthrough and Rush. They can also get on top of the first B site on breakthrough in Siege of Cairo. And of course they're all on the roof on New Sobek City.
How has this now been fixed yet, it's been happening since launch.
It would be different if the buildings that they're on could be destroyed but they can't so whoever goes up there has a huge high ground advantage over everyone else.
The drone glitch needs to patched ASAP, but you can also use the tactical ladder on some of the maps to get up which kind of makes sense, but again you either need to make the buildings destructible or stop people getting up there entirely