Click the "Recalibrate" button in the bottom left
(transparent button over the camera image)
This happens when your lighting changes. LASR X does require consistent lighting (other than laser impacts) in order to work reliably. Oftentimes, LASR X can recognize lighting changes that don't look like laser impacts and will suggest that you recalibrate, but not always.
If you are seeing this a lot:
Most commonly: That the targets and webcam are not wobbling/moving around, and that the shooters are not moving between the webcam and the targets.
Back-lighting is causing the shooter, or something or someone else, to cast shadows over the targets. Those shadows cause changing light conditions. You will want to remove the source of the back-lighting, or use additional fill lighting to eliminate the shadows.
Natural lighting from the sun is dominating the light in the room. The sun moves throughout the day, butts move in front of the sun, and light levels in the room and on your targets change accordingly. You will want to take steps to eliminate this source of changing light, like closing curtains, or even moving to a different room.