have you check the swamp areas? they are a somewhat rare spawn in that area. some days we have 1-2 roaming arround and other times we have multiple days where there's simply nothing.

I looked at everything.
They just did not spawn, they were gone a week, until I used the command that destroyed all the wild creatures and they appeared, now they're gone again ...

Let me tell you how spawns work, each dino has a weight assigned to it, the map when replacing spawns will pull the dinos randomly based on weight for that spawn container(assuming the crabs are a low weight and have a limiter on them.)

There is going to be times you just don't see creatures because they have not been selected for respawn.

If you don't see something kill till it spawns, that is just how the game works.

AS for wyverns and rock drakes not spawning thats an anomaly i cant provide any information on as i have never had that issue with this map.

We've had our Volcano server running for about a month with 7-8 active players. Nobody has seen a single Karkinos spawn yet. We just assumed it was not set to spawn on The Volcano.