Am I missing something with regards to Death Saving Throws?

Having to roll a d20 is not much of a hardship, but I would have expected a button that you could hit when it was your turn that handled a) the rolling of the d20 and b) the marking of success/failure for each roll.

I've had players reach a point where they needed to roll for Death Saves a few times, but I am still surprised that there are no features for a button click to do the work.

On the character sheet, you need to reduce HP to zero. At that point the HP area changes to a death save display. Click on that and you will see what you're looking for.

Yes, I saw that recently. But unless I'm seeing something different to everyone else, all I'm getting is a set of boxes to click upon a success or fail. There is no button to activate a Death Save roll itself, you just have to roll that yourself separately. 

I'm OK if that is the way to do it, but I'm surprised there's no button.

I am also missing what Scat is pointing out.  No way to roll a DS except custom roll.  I too would have expected a click to roll button that would auto populates the ticker.

Another disappointment from the activity side of DnDB.

Possibly because of the options the game provides to either add additional rolls or replace a roll, the developers figure it is better to roll a d20 and than apply benefits to see if this results in a pass or fail.  

Also, it is possible other actions can result in downed character to be brought back to consciousness or automatically failing a death save.   The field is designed to modify the status of the downed player. 

This is due to the fact very, very little affects death saving throws. Some things may give advantage but almost nothing gives a bonus. There are no modifiers for death saving throws. It's a straight d20. You can already roll a straight d20, with advantage if needed, by clicking the icon in the bottom left. 

If you go on the app, this feature exists:

You do have to come off the health screen where you alter your HP and go back to the main sheet. I think they should have put it on the health screen personally (or both). If you roll using that feature, it automatically applies the result to your Death Saving Throw counter.

They have omitted this feature from the desktop version of your character sheet. I don't see why they wouldn't have included this basic feature, while small, this kind of automation and slickness is what DDB sells itself on.