Hi,
You haven't provided the scripting code for your custom action com.vmware.andrew/getDatastoreForHost_AC but most likely it doesn't handle correctly the case when its input host parameter is null/has no value.
So probably your action's body is:
// 'host' is the action input parameter of type VC:HostSystem // if the input parameter is null -> the statement below will not work correctly and you won't see the expect drop down return host.datastore;
The correct code would be something like this:
// 'host' is the action input parameter of type VC:HostSystem
if (host == null) { // input parameter is null -> return empty list of datastores (not null) return [];
} else { // input parameter is not null -> return the actual list of datastores return host.datastore;
}
At the beginning when you start the workflow but still haven't selected a valid host in the first drop down, the Host value will be null and com.vmware.andrew/getDatastoreForHost_AC will be called with null input.