Issue Summary

When editing a customfield select list (multiple choice) it should be possible to use add or remove like with a label.

Steps to Reproduce

1. Create a custom field - select list (multiple choice) with available options.
2. Create an automation rule to modify the custom field.
3. Only the copy and set options are available via the menu (...)

Expected Results

It should be possible to use add or remove like with a label.

Actual Results

It is not possible to use add or remove like with a label.

Workaround

Use the additional fields section to add values without replacing existing chosen values:

{
  "update": {
    "customfield_10240": [
      {
        "add": {
          "value": "4"
        }
      }
    ]
  }
}