Why do some components vanish from the catalog list if one component has been installed in Rancher? If one adds a component from the catalog in Rancher and one would like to add another component than the list seems to be reduced. Why do some components vanish from the catalog list if one component has been installed in Rancher?
You haven't specified anything concrete, so I can't give you a specific reason...  But catalog items can:


Be mutually exclusive (e.g. you can't use ipsec and vxlan at the same time)
Be deployed at most once in an environment
Require the environment be a specific orchestration type
Require a certain range of Rancher versions
etc