If it’s drawing a rectangle on the screen that remains behind, then the LightBurn Rectangle tool is active:
Instead of the Select tool:
The tinted icon in the stack over on the left of the workspace shows which tool is active. The Select tool should be active / tinted when you want to pan or zoom with the mouse, rather than draw shapes:
Source: Been there, done that.
You can, however, pan while the other tools are active with a press-and-hold on the middle mouse button while moving. Press-and-hold while rolling the mouse wheel will zoom the workspace, although that’s difficult on my trackball.