BUG(?): Possible funny interaction with AoTD.
If you have AoTD installed, that enables "age of innovation" thing which makes the AI upgrade their colonies.
In my playthrough, for reasons unknown to me, Ava Nitia started hating my guts completely (-100 relationship) without me doing anything specific to *** her off.
I suspect that what actually happens was that Chizomoztoc got the age of innovation, which caused the AI to upgrade its orbital works to a better facility, but in AoTD, these better facilities do not take nanoforges, they don't take any items in general, which caused the nanoforge to be lost. I was at war with IRS at the same time, so I thought Eternal Lion and co. being sent after me was normal, but now I suspect it was the chizoforge retaliation fleet.
Some safeguard may need to be placed to ensure that it was the player specifically that stole the nanoforge.