This is because `concatenate()` is an aggregate function (i.e. it looks up the values for that attribute across _all_ features), so when you try for example `concatenate("GROUP")` you'll still end up with a whole lot of results (the `GROUP` value for every single feature) joined together - e.g., `Wianamatta GroupWiannamatta GroupWiannamatta GroupNarrabeen GroupNarrabeen Group` and so on, for a *single* label. 

When you use `concatenate()` with multiple fields then all those fields will, again, be represented for every single feature in your dataset, even though the label is only for one feature. So in your use case this is simply not the appropriate function, even though `concatenate()` does let you specify delimiters which is handy.

`concat()` is the function you are after but it takes each field as a parameter, rather than you having to concatenate it yourself using pipes (`||`). However, you still have to manually insert each delimiter and the appropriate space after every single field reference, which is quite tedious.

For a more elegant approach that handles `NULL`s better, consider array functions:

```
array_to_string(
    array_filter(
        array("GROUP", 
            'Ref: '||"Lett_Sym_1",
            "Formation", 
            "Period"|| ' age',
            "LITHOLOGY"),
        @element IS NOT NULL),
    '\n\n'
)
```

This converts the relevant attribute values, with appropriate prefix/suffix, — e.g. `Narrabeen Group`, `'Ref:'|| Rnbh`, `Bald Hill Claystone`, `Triassic||' age'`, `Dominantly red shale and fine to medium sandstone` — into an array (`['Narrabeen Group', 'Ref: Rnbh', 'Bald Hill Claystone', 'Triassic age', 'Dominantly red shale and fine to medium sandstone']`).

This array can then be filtered using `array_filter()` so that if for example `"LITHOLOGY"` is `NULL` it will remove it from the array. Or if `"Lett_Sym_1"` is `NULL` then `'Ref: '||"Lett_Sym_1"` will also be `NULL` and that entire element will be filtered out.

The resulting array can then be converted to a string (i.e., text) using `array_to_string()` with your specified delimiter to use after each element of the _resulting_ array (remember, this is already filtered to remove `NULL`s so there won't be unnecessary delimiters after a `NULL` value). 

As `\n` is a linebreak, the above expression does not even require you to wrap on the `*` character. 

The benefit of this method is that you can easily add more fields or change the delimiter as needed without the tedium of editing a long `concat()` expression, or worrying about whether you need an additional space, or if you've got a text prefix like `Ref:` hanging out on its own without a corresponding non-null value... (in which case, don't replace all the pipes with commas!)

---

Example dataset with `NULL` value highlighted:

[![enter image description here][1]][1]

Result:

[![enter image description here][2]][2]


  [1]: https://i.sstatic.net/OZWuv.jpg
  [2]: https://i.sstatic.net/c2Dtm.jpg