When will it be avaliable?

What exactly are you trying to do?

@Teodor ,
you will get this message when click to lightning icon …

( at parameters properties )
other lightning icons working very well

Looking at your screenshot, it seems you’re trying to using the ‘Join’ function. This option is already available, but not yet possible using the interface (as far as I can see). You can manually enter somthing like this:
{{query1.join("<br>", "item_summary") }}
… and it works fine.

I think this problem - and this error message - have been mentioned a few times, so I expect this will be fixed soon.