This seems to be a rather rare bug due to the fact that I have only found 1 thread related to it and that thread is on steam. Since I don't want to pay $5 to reply to the thread, here we are.

A quick summary of the bug: unnamed enemies that have been previously killed, such as a raider waster in federal ration stockpile, will sometimes respawn "playing dead." When an enemy is affected by this bug, they cannot move or attack. Killing an enemy affected by this bug will make their body unlootable unless any part of their body has been severed. ( for those with the bug, you can melee a body part until it is removed and then loot that body part, gunfire will not work ) occasionally their body will also be thrown out of the map making loot entirely unobtainable. Legendary enemies can be affected by this bug. Entire dungeons can be affected by this and ultimately ruined.

The cause: The Cryolator. I have spent at least 5 hours testing this because this bug has completely undermined my "infinite gameplay" doing radiant quests and going all out on settlements. When I kill an enemy with the crystalizing ( cant confirm if barrel mod matters ) and wait roughly a week, they will respawn in this "playing dead" state. My character was heavy weapons from the start, and there's no ( non wide effect ) heavy weapon better than the cryolator, so I killed god dang everything with it for the first 40-50 levels. I did not use the dogmeat glitch, so it cannot be related. I have also never encountered this bug in a dungeon where I killed everyone with any other weapon, even ash piles and goo piles properly respawn if they are in an area where enemies respawn.

In total: Please, let this information lay the foundation for a fix to this bug. I do not want to create another character exactly the same as this one just to get radiant enemies back.