It should be: On a long rest, reset to one use.  On a short rest, add one use if at zero.

Right now: long rest resets it to zero and a short rest does nothing. 

Are you talking about the Fighter's Action Surge?

Can you post a link to the affected character?

Power Surge, the War Mage subclass feature. 

Short rest was not resetting either my Fury of the Small, not Action Surge yesterday for my Goblin Battle Master as well, I had to do it manually twice. 

Got it. Yes, that does look like a bug, or more likely, a feature that DDB can't correctly support with their current toolset. I am able to reproduce it as well.

For mods / staff, example character here: https://www.dndbeyond.com/profile/Houligan/characters/21409479

Hello! The unique way in which the Power Surge feature can reset is not currently supported in D&D Beyond, as it has many varying conditions for recharging its uses. I have marked this thread as 'request' for now. Thank you!

That is what I was guessing. Pretty much every other mechanic recharges on either a short or long rest, but not both. And when you look at the Actions tab when making a feat / subclass / race, you can only specify one reset condition.

I came here looking for this exact issue so I can confirm it hasn't been addressed yet. TX

As of January 2023, this is still broken. Same as described by everyone.