While at my raid farm I noticed one of the waves wasn't coming down the chute. It took a while to finally find them outside the raid range. The raid bar didn't show up at the top of the screen in the area they had spawned (a few hundred blocks away in one of my castle towers on top of carpet...). There were three people in total on the server all in the same area. Once the wave that spawned outside the raid range was dealt with the remaining waves spawned in the raid farm (which is above a pillager outpost) as normal.