I have an issue with some former mission relevant ship of the Free Families (Slave Trader # / A Split Buffalo) which apparently didn't get the memo of the finished Split Plot and stays indestructible.

While checking the save, I've seen an entry with "min hull = #" which is exactly the number of hull points the ship maintains, even when under fire of I's, K's, and the typical swarms of smaller critters.
The savegame I experience this issue was started with 4.2 and was carried over to 5.x and now 6.0HF5.
The plot was started in 4.2 up to "deliver Fleet to Curbs (either sabotaged or not)" and completed with 5.1 with the sabotage and destruction of the Curb's Raptor, followed by the extra payment to ZYA to cut the piracy down.
All CUB/CAB installations and vessels are destroyed and the former Systems and Sectors where repopulated with Xenon.
Due to a missing game mechanic to set a faction destroyed for good if "insert arbitrary variable here", the Curbs place a new Build Site for the Trade Station/HQ as soon as the last one is destroyed.
The Xenon took hold of all of the territory but a bunch of pesky stubborn Buffalo's still roam freely without any order, indestructible, aggravating all Xenon around and even eliminating whole fleets in "self defense".
I don't know if this was already patched within the last years for new game starts or if it's just bad luck and/or a script hickup on my end, so I don't consider this post a bug report per se and ask for technical help to alter the vessel's entry directly in the save.
Anyway, I would be very, very (insert another superlative here) happy if someone could tell me, what I can alter in the entry of the Save to get rid of this Gallic Settlement... I mean... Slave Trader # Buffalo without rendering it corrupted.
Screenshots for clarification:
https://imgur.com/a/xy41edd
And @Alan: Before you tell me to rtfs:
No, I don't care about "modified" flag.
Yes, the game runs some small mods.
Yes, the save can still be loaded in vanilla.

Thanks and have a great time,
Nilus