In the advanced options, you can try creating a rule that if the object ID is not blank, center the text and apply to the whole row. For some reason, it didn't take until I also set the text color to black.
Hope that helps!
To discover text mode methods I often try to get what I want in regular mode, then I switch to text mode and read the code.
Thanks Sarah, that's really useful.
Do you know if it is possible to centre the field name as opposed to the data that is pulled through?