I have A250T printer. I can’t figure out how to get a different thickness after the first laser engraving on a 1.5mm thick sheet.
Are you running your jobs directly from Luban or transferring the file and starting on the touchscreen.
Either way, you will only be able to choose material thickness if you are using auto focus rather than manual.
If running from Luban, when you click Start on Luban, a dialog box will pop up, select Auto and then you will be asked for the material thickness.