-I was playing as a Necron with 2 Cairn battleships.
-I went against Tyranids. Soon after my initial attack one my battleships became a drifting hulk and I scuttled it.
-Soon after my flagship also became a drifting hulk, but the "Scuttle" option was not available.
-I was able to board the flagship with some troops and reactivate it. But soon after it became a drifting hulk again. However, this time I was able to scuttle it.

Hi, i'm unable to reproduce unfortunately. I'll keep an eye open for it, thank you !