Static mesh falling through landscape

My actor has a static mesh component with these settings set in the constructor:

RootComponent = MyMesh;

MyMesh->SetCollisionResponseToChannel(ECollisionChannel::ECC_Pawn, ECollisionResponse::ECR_Ignore);


I spawn the actor in the air and it falls to ground like expected. But sometimes it falls through the landscape for unknown reasons. I have checked the collision on the mesh and it has both simple and complex collision. The landscape is set to Block All with a default thickness of 16.0. For the mesh the trace and object response are to block everything but the pawn. I have set show collision in the editor and I can see the collision shown when it drops from the air.

Most of the time, it lands on the ground just fine. But sometimes it falls through the landscape. Has anyone had this happen before and know what could be causing it?

How come it only works like expected some of the time?

MyMesh->GetBodyInstance()->bUseCCD = true;