So this is actually a good example of the difference between the bug reports we get and the ones we're looking for ^^
"killed Sulo on hard/elite,chest still not dropping"
Instead you can actually be more verbose and write a description just like what you wrote in your post:
I know this seems 'lengthy' but in some cases something may very well be WAI, and reports like this help from a "quality of life" stand point. Maybe the intent was for it to work the way it is? But if we're getting bug reports from people who are confused, it gives the quest folks leverage to change it. Not always, but it's added ammunition.
Very often people try to "abbreviate" their bug reports, and really you shouldn't worry about writing reports in short hand. Detailed bug reports are nutritious and delicious.
As for the chest itself, I'll ping the QA folks to make sure the reports they've gotten are telling us what we need to know. If now, I'm sure one of them will come prowling.