It's bugged right now. It was supposed to work with armour mods, and I think weapon perks as well, but in true Bungie fashion, the patch that was supposed to make it work failed. Not sure if it's a known issue or not, so I'd highly recommend making a bug report in the Help section. The more people -blam!- it, the less likely Bungie will be to ignore it.

I don't believe that's bugged. Essentially on launch ascension was breaking the game due to being essentially infinite so bungie removed it's "Class ability" status and now they've given it some things it can work with and said if it still isn't good they'll give it more. Rn it seems decent but I think they'll give it a few more if I had to guess.