Procedure seems to be causing dedicated server freezing/unable to join

When players fly (the procedure) it seems to freeze their game on dedicated servers and disables them from joining back. It can even happen when other players are flying as well I’m pretty sure. Help would be amazing, as I’m trying to get an update out really soon. 

procedure:

https://files.fm/u/q8y9hme88y

Also, here is the code snippet integrated into it.

if (entity instanceof Player player) {
           player.getAbilities().flying = (creativeFlight == true);
           player.onUpdateAbilities();

           if (player.isFallFlying()) {
               Vec3 lookVec = player.getLookAngle();
               Vec3 flightVelocity = new Vec3(lookVec.x * flightSpeed, lookVec.y * flightSpeed, lookVec.z * flightSpeed);
               player.setDeltaMovement(flightVelocity);
           }
       }