round trips between advanced and simple search with multiple label custom field search

Doing an advanced search of more than one label presents you with the option of converting to simple mode.
But converting to Simple mode and then running the search generates an error.

to reproduce

1. add a labels custom field. Let's call it Tags
2. search using this JQL

   Tags in (labelA, labelB)

3. Click simple to switch to simple mode
4. Click Search

Expected result
search runs

actual result
Error Message

More information
The problem lies down in the LabelsCFType code. The "todo" comment is mine

  private Object convertStringsToLabels(final Collection<String> labelStrings)
    {
       final Set<Label> ret = new LinkedHashSet<Label>();
       for (String labelString : labelStrings)
       {         //todo - search input comes through this - in which case it could be multiple labels in one string
          ret.add((Label) getSingularObjectFromString(labelString));
       }
       return ret;
    }