This is a verified bug in the Mac version of 2.0.03. Please see:
@Xina
Do this, please:
Install version 2.0.02 from here: https://release.lightburnsoftware.com/LightBurn/Release/LightBurn-v2.0.02/LightBurn.V2.0.02.dmg
You don’t need to add your device again. Instead, restore your settings from a previous state:
First, save your current file, then open a new blank project from File > New in the top menu bar.
Then, go to ‘File > Preferences > Load Prefs Backup’ in the top menu bar.
The preferences backup window will appear. From the list, select a time and date when everything was working as expected.
Then click ‘Load’ in the lower right corner.
This will restore your prior settings and should restore the connectivity.
(Having access to GLaser is a good way to rule out other issues.)