This happened on a multiplayer server to which I don't know the seed. Hard difficulty (local difficulty: 3.38 / 0.69). A raid took place on an island with 1 villager surrounded by at least 36 blocks of water. The villager was completely covered in blocks. Raid members would have bizarre AI, as if they had amnesia.

Pillagers and Vindicators were the main victims - not only did they not approach where the villager was, but they wouldn't even attack me, not even when I began attacking them. Occasionally they would fight back, usually at the end of the wave, when there are just a few left. At one point, one Vindicator began swimming away from the raid, paying mind to nothing else. Ravagers would occasionally get confused, but would usually start fighting me after a short time (the ravager's rider would also always try attacking me, as normal). Evokers and Witches were mostly unaffected, with the exception of not approaching where the villager was. I would fight the previously 3 mentioned raid mobs first, as the Pillagers and Vindicators would stand and do nothing - they seemed almost innocent, that I didn't want to kill them. Pillagers would look at me funny, which can also be observed when in Creative mode, but nothing more, except for when the occasionally would fight back.

 Images:
Images 1 and 3 are me standing with a wave of just Pillagers and Vindicators. I even talked to them a little. These two images are two separate raids, plus a third later raid went down without issue, so I'm confident it's the location. (second image is in F1 mode)
Image 2: The previously mentioned Vindicator who swam off in one direction. Note that this was not the direction my villager was. He chose it by his own volition.
Image 4: A bird's eye view of the area. The granite area with the firework particles is where the villager is located. The landmasses to the left, top right, and bottom right peninsula are where the raid mobs spawned.

If more information is needed, I would be fine with providing it.
See also: Don't know if same, but seems like it. https://bugs.mojang.com/browse/MC-150146?jql=text%20~%20%22raid%22