Bug? Dacha occupation

[bjamminloe]

The Helito system ended up in another civ's borders, and they didn't do the proper path, so Dacha became an isolated civilization participating in the Galactic Council. I decided I needed those gaia worlds, so I claimed the system and invaded.

I conquered them, occupied all their planets, and they have 100% war attrition, but will not surrender.

The peace negotiation says I have -50 for unoccupied systems, and -100 for unoccupied Dacha.

https://steamcommunity.com/sharedfiles/filedetails/?id=2954001621

But when I hover over the system, it shows it as 100% occupied by me:

https://steamcommunity.com/sharedfiles/filedetails/?id=2954001669

What an annoying bug.