How do you use the spell "Arcane Vigor" and other similar features?

Arcane Vigor has you spend hit dice to use the spell. How exactly are you suppose to spend the hit dice?

The only way I seem to be able to bring up my Hit Dice is to click the Short Rest button, but I cant manipulate them directly without taking a short rest. If I mark or unmark any of the boxes, when the window is closed, it doesn't save those changes and they revert to whatever they previously were.

Alternatively I can do a short rest to spend the hit dice at least, but that conflicts with various features that reset on a short rest.

So what do I do here? Is there no support for these features? Is it a bug? Is there another way to manage this?

Quote from spamandtuna >>

Yeah, that’s not currently supported.

 Isn't that kind of a problem? This isn't like an obscure spell in a small supplemental book. This is a Player's Handbook spell.

Over a year later and this still doesn't work. There's no way to spend a character's hit dice without committing to a short rest and having that update all short rest abilities on your sheet accordingly. It is wild that a Player Handbook spell doesn't work on the official character sheet platform for 5.5e...

It's one of many things that the site can't support until they rebuild the back-end, which they are currently doing.

Quote from EverydayEnthusiast >>

Over a year later and this still doesn't work. There's no way to spend a character's hit dice without committing to a short rest and having that update all short rest abilities on your sheet accordingly. It is wild that a Player Handbook spell doesn't work on the official character sheet platform for 5.5e...

 WotC BOUGHT Beyond from the original developers who didn't have the tools to model everything in the 5e game, much less the 5.5e version.  They are rebuilding DDB from scratch on the back end so we will get many if not all the features supported.  

The current version is like taking a bicycle and one of those kits to make an electric bike, it works but lacks some features.  

The new version will be like a real e-bike, fully integrated and designed to work together from the start.

At least I fervently hope so.  Until then pen and paper still work.  I use a small chalkboard for these items.

Enjoy your game, even missing some features DDB cuts down on a lot of paperwork!