If a USB port type is not showing up in LightBurn it’s almost certainly not going to be an issue with LightBurn itself. It’s going to be an OS issue where for some reason the USB device is not being identified, loaded, and presented as a USB serial device.
Key should be to focus on why MacOS is not connecting to the device correctly. Typically this would be a driver issue. Rather a matter of not having the driver. However, since you said this used to work there’s likely something else going on.
Has anything recently changed on the computer? Any OS updates or perhaps did you install yet another device onto the computer recently?
I believe the Sculpfun lasers use CH34X USB Serial chipset.
Check this post for context and a link to how to check and reinstall the driver as necessary: