I was testing out the Laviathans when I noticed I couldn't control them if they were naturally spawned. They had the saddle and helmet equipped, but I couldn't move them when I was riding. I then spawned some with spawn eggs and I could control them just fine. The only mods I'm using are the latest Alex's Mobs / Citadel and OptiForge (OptiFine isn't fully compatible with Forge 1.17.1 yet). I was also using the latest Minecraft Forge 1.17.1