If you get disconnected during a map with a corrupted nexus, the nexus disappears and the corruption is not cleansable.

Same, reported it on the official forum. I lost my second corrupted nexus due to dying in the boss fight. I'm at t15s now and have 4 atlas points lol.

I thought the “loss to boss = lost nexus” was a feature not a bug. Really made me “feel the weight” every time I was fighting a nexus boss.

Getting disconnected on any map means you lose the map. When the disconnects cause rollbacks you even lose loot you picked up too.