' Call Service Node' has no entity ID

In that case, if it does not work with any service / entity, it may be something to do with your Home Assistant server connection.

The HA server configuration node sets up the WebSocket connection, and this node has settings to capture the HA state and to save it in global context. Also there are settings for the ‘Cache Auto Complete results’.

As a first step, check your NR Global Context for a variable ‘homeassistant’ and look in this for your HA object, and for the ‘services’. This is where the node gets the service values from, and it then looks in HA for the entities.
Sometimes the Autocomplete Cache needs to be toggled (if on - off, if off - on) just to try and see if that fixes the issue.

Otherwise, the usual - have you updated HA, Node-RED addon, WebSockets, Companion to the latest versions - applies.

This is where the home assistant configuration node can be found (I just happen to have two) Your one will probably be called Homeassistant.

The ‘Enable heart beat’ sometimes helps with keeping a dodgy connection alive.
The ‘Enable global context store’ is required to keep an HA state copy in global context (see below)
The ‘Cache autocomplete results’ helps with speed of getting the drop down lists populated, but caching can cause issues…

This is where to find the global context - there should be a nice homeassistant variable in there with all the states and the services - this is what is used for the service auto complete!

As a workaround you can put the entity_id in the data field.

{
  "entity_id": "number.volume"
}