- Near the end of the game, the option to offer to Attack a race disappeared (I only had the option to surrender)... all of the three remaining races were aware of each other (in fact, two were engaged in a war and I was trying to offer to come in one side). I think this was right after switching to an Interstellar Republic, but I switched back and still didn't have the option.
Are these known issues?
I have seen this although not often enough to be sure exactly what's going on.
In my case I was able to offer to attack only a few turns before and like you it was also immediately after switching to some higher form of government. Also switching back made no difference, but I assumed the issue was that once you've needed senate approval for war it removes the option to offer to attack.
In my case I had a save game not too far back before I switched government and so I went with that and didn't change governments and was able to offer to attack when I wanted to.
Anyway I haven't really studied the issue enough to understand precisely when you can and when you can't make an offer to attack. Perhaps someone else knows the answer but usually it's best if you have a save game exhibiting the behavior then you can play around with it trying different things until often you can figure it out yourself and then let others know what you found.
As far as ships I think if you're at war with them then their ships don't show up. As DA mentions any ships in fleets never show up but its very rare that an AI doesn't have some loose ships floating around or at the very least starbases. Were you at war with the Drath at the time?
[edit] One possibility on the government change is that perhaps you cannot attack until you've won your first election. It's only a guess but it's things like this that you can check out, because I do believe that there have been other cases where I was at a higher form of government and still was able to offer to attack. [/edit]
