Could you pastebin your team file please?

I just tested it, yep, the team cannot be added online, I can reproduce this.
I looked into the file and saw the team does not have a voicepack for some reason, in the HWT file it says “Voicepack=” without a name.

Try setting the voicepack in the team editor to “Default” or any non-suspicious voicepack and it should work again.

But it is weird, why the hell did the team file have no voicepack in the first place? And how could it have happened (This question goes to the developers )

Terror, before this has happed, have you used any custom voicepack or a voicepack with unusual characters in its name?
Or did you change anything else?

terror, did you place the custom voicepack in global hedgewars directory? If so upgrading erasing that would not be surprising.
The frontend editor would try to match something nonexistent and the list would be blank.

You should be able to keep voices under ~/.hedgewars/Data/Sounds/voices (My Documents/Hedgewars/Data/Sounds/voices if in windows) though. Hedgewars wouldn't erase something from under there (although other programs might, who knows)

I'm inclined to go with. "not a bug"

I think this is kind of one of those PEBKAC edge cases here I think due to user modifying global install, which they aren't really supposed to do. That's why the ~/.hedgewars exists in the first place ☺
If you'd put it in ~/.hedgewars at least you would have known if you'd blown the voice away that the team used.

As it stands now, I expect this will be waaaaaay down on the list of things to be addressed, esp what w/ the desire to ditch current frontend. But maybe for the new one!

There are tons of ways you can blow up the game by modifying resources. That's sort of an "at your own risk" thing.