I’ve played the solo content multiple times. After nerfs when people claimed it was now impossible, I wanted to try. I’ve never needed more then three or so tries.
Difficult? Yes. Impossible? No.
If you run into bugs, report those bugs here. Preferably with a screenshot or a link to the game on hsreplay.
If you have evidence of hacking, report it as requested at How to Report Hacks/Exploits/Cheating (though I have no clue how that would work in solo content, but that’s not my problem)
For feedback that is not specifically about bugs, please use the other forums.
This forum is only read by staff tasked with checking bug reports.
After the next expansion, the method of unlocking Demon Hunter will change to match how other classes are unlocked. This has been announced a few weeks ago already.
Some options being unavailable when Demon Hunter is not unlocked is most likely a bug. It happened before and was fixed, and is now unfortunately back again. Given that the next major update will be one of the biggest since the start of the game, I would personally not expect any bug fixes between now and that update (but I am more than willing to be pleasantly surprised).