Doing a raid on my vanilla minecraft server with a friend, and we did a raid. level 5 bad omen onto wave 4, and there was one mob left at the top of the screen but he progress bar was empty.

went into spectator to look at the caves underneath, nothing. used a bell to see if we could use the glow effect, nothing. the enemy was missing and the bar was empty. an enemy was seen going into a cave, but that could also be a loose end. it could've died in the cave to either an iron-golem, lava, drowning or fall damage. but whatever it was, it bugged the raid and caused it to be unable to finish.

 even attempted to use execute commands to teleport it to me, but I'm not very experienced with them and could have easily fucked it up. We eventually just pissed off as it was a waste of time.

The village was really weird generated on terrain so that could have contributed to it.

Thanks in advance.