Almost certainly you have the honeycomb bed visible. The honeycomb bed looks like a LOT of circles and basically hangs the software trying to sort them all out. (this is highlighted in the documentation)
Common mistakes and solutions:
The most common problems people have with the lens calibration are as follows:
Honeycomb bed is visible, confusing the circle-finding code. Cover the honeycomb with a bed sheet, cardboard, paper, wood, etc.
Camera isn’t in focus. Focus the camera as well as you can to get a clear image. All of the LightBurn cameras are manually focused by twisting the lens
Calibration pattern is too small (or too large) in the view - you want the pattern to fill roughly one of these squares for each c…
The actual instructions: (notice where it says “Important” on this page and tells you to cover the honeycomb)https://lightburnsoftware.github.io/NewDocs/UsingACamera.html#the-camera-lens-calibration-wizard