It would appear that there may be a small implementation error with the Bugbear 'Surprise Attack' racial ability. Unlike the Rogue ability 'Sneak Attack' there is no 2d6 dice box associated with it when I try to display it as an attack like Sneak Attack is on the character sheet as an attack action.

Just create custom action for it, if you really need it.

Quote from Cyb3rM1nd >>

Just create custom action for it, if you really need it.

 To be fair, I'd been wondering myself if DDB could go ahead and add the dice elements etc. for already-defined Actions like this. It seems perfectly doable with the current UI. There are other cases I can think of where this would be helpful as well.

I tried. It showed up but there was no way (that I know of right now) to add the 2d6 damage dice to the custom action.

On character sheet in actions click Manage Custom

Using the Add New Action dropdown choose General

A new action is created showing as Custom Action # (where # is a number). Click it, and choose edit. Edit the following options

Dice count: 2

Die Type: 6

Activation Time: 1

Activation Type: Action

Check the Display As Attack Box

For Name put "Bugbear Surprise Attack"

For Snippet and Description copy and paste the racial feature: "If you surprise a creature and hit it with an attack on your first turn in combat, the attack deals an extra 2d6 damage to it. You can use this trait only once per combat."

And voila. You now have the 2d6 displayed in your attacks.

If you get acquainted with using custom actions and custom items this way, you get a lot more control over the sheet for all sorts of things. If D&D Beyond are not able to automate, no biggie, add it yourself in no time. This custom action took me 12 seconds to make.