Never mind; It looks like I actually do run at a deficit with the deuterium synthesizer off and the fusion reactor on. It's only a problem in the resources window where daily deuterium is calculated.

Oh my...

...And it looks like I can run my fusion reactor even without any deuterium; I've got -39 deuterium showing right now..

Hmmm, I dont build fusion reactors at all so I cant check mine to back you up with this one.

Hopefully they fix it.

It occurs to me that running at negative deuterium might be a good deterrent to attack, if the formula determining winnings ends up transferring negative deuterium to attacking players.

I forgot how it works exactly but it doesnt take their deuterium, I think it just gives them zero but keeps you negative

The issue is known but not important.

Regarding raids, It does not transfer any negative deuterium from what I know.