‘Target buffer size found’ is what LightBurn says when it first connects to a controller, and queries it for some basic info. That’s not an error, but it tells you that the board disconnected, then reconnected, and that’s relatively common. It can be caused by:
- Poor quality USB cable (no shielding or ferrite rings)
- Poor quality power supply, or not enough power for the laser, causing brownouts
- Electrical noise induced in the USB connection
- Static electricity discharge
- USB port power save / sleep
Some of these are covered here: How to troubleshoot connection issues with USB