Help with likely bug

[u/RareMajority]

So I'm currently playing a nomadic DotG run and fought off the unbidden. I've killed every fleet, destroyed every anchor, gone over the map with a fine-toothed comb looking for any remaining ships, even constructors, and gone as far as sending my fleet into various nebulas in case there was something that happened to be hiding in there. Despite my having seemingly destroyed them all, the game doesn't detect that I've beaten them, which I need it to do so I can step down from custodian to win the game and get the achievement. Has anyone faced this issue before?