Might be that there is no data, or created_at is not a valid datetime. I would try the repeat without the formula first with just repeated.current.created_at to see what’s going on in the field.
Yes I tried to display just the time stamp as suggested. That’s works and displays the time stamp in the app preview and composer Pro.
Using the formula as above does seem to work in the composer Pro screen as I can display the data as defined by the formula out put “DD.MM” for example or “DD.MM.YY”
So it seems to be able to read the time stamp ( from Xano).
But it does not display anything in the app preview.
If ‘repeated.current.created_at’ is a Timestamp in Milliseconds then you need to convert that to ISO 8601 format first using the DATETIME function, ex: DATETIME(repeated.current.created_at)