doublemoses

If I read the code correctly, the patrol spawn sequence is this.

In the xz location it picks, it finds the highest movement blocking block in the column that isn't leaves (in this case that would be the log block), checks if it's a spawnable block, and checks the block light is 8 or below. It doesn't do a check to see if the foot/head blocks of the pillagers are obstructed, and just spawns them in if those other checks are satisfied. I believe this also means they can spawn in on carpet, which was what I was trying to figure out when looking into this

I guess this is done this way so that patrols can spawn in forests underneath trees. Adding one more check should make it work as intended.

The first time I got the issue was in a world that was started in 14.3-pre1.

I know why the observers aren't firing, and I know how to fix it, but I don't know what causes the bug in the first place. I've been trying to recreate the cause of this for a while but haven't been able to figure it out. I've had it happen to me with torches and repeaters.

If you use NBT explorer to open the region file (r.-1.-2.mca in this case), and go to the chunk with the observers (-32,-43), you can see a bunch of entries in the Level>TileTicks section. Most of these are oak leaves, but there are a few that are observers. Deleting these entries from the region file will make those observers work again.

That was pretty much what I expected, but what I wasn't expecting was for some of the observers to still not work. Turns out that some of the observers tileticks are in the section for the neighboring chunk (-32,-42), instead of the chunk they are in. Deleting all the tileticks from both chunks made all the observers work again. This makes me think that maybe the game sometimes tries to add/remove the tiletick entries to the wrong chunk, and that's why they aren't being cleared out correctly.

Someone I was talking to thought that the issue happened to them when they died, and the two times I had it, I noticed it after I died as well. Not enough for me to say it's a direct cause, but it's a possible link. I haven't been able to find a way to cause the bug yet. I'd be interested to know if this happened immediately after you died as well.

It happens at any y level that is a multiple of 16. The top of the banner is in a subchunk that isn't in view of the camera, so I'm guessing it doesn't check to see if the bottom of the banner needs to be rendered.