I completed all of the Cyberpsycho missions but one remains labeled as incomplete- Where the Bodies Hit the Floor. I killed the guy and read both of the associated shards but the quest won't clear. Also, if you look at the Cyberpsycho achievement in GOG Galaxy, you'll see that it's only at around 16%. That's pretty low compared to all of the other ones. Am I not the only one having trouble unlocking this achievement?

The achievement is not broken, but it might be you have a bug. Do you happen to have an earlier save so you could try to complete the Cyberpsycho sighting again? Often loading an earlier save is your only option.

I have a similar issue in Biomutant where I cleared out all bandit camps, but one of them did not get marked as completed. So now I have a side quest pointing to an empty bandit camp. And of course I have no save from before clearing that camp.

Patch 1.23 came out today and in the notes there is a fix for this specific bug. So it looks like it's no longer an issue.

I can't finish the quest, because Where the Bodies Hit the Floor. it has been done but is not counted