I have had a hunt around for about 20 minutes, but figured my best shot was probably asking someone on here who has more experience!
Have you tried “Nest Selected” in the “Arrange” menu?
Did you try doing it with this
Another way to approach your design would be to make a single object with the variable text, and make an array
Or the option that was recommended to you above.
Save your project as SVG, upload it, Nest it, then download the nested SVG. Load that into Lightburn and you should be good to go.