If you look in the window screen there are 2 settings.
Silhouette cameo mat not loading properly.
The fix is to move the paper or material on the cutting mat over and up just slightly so it covers the top and left edge of the grid line box right.
When loading the mat into your cameo the left edge of the mat should be aligned with the alignment marking on the far left of the machine.
The fix on the silhouette was i had accidentally changed the settings from load cutting mat to load media.
These are the top 2 user errors i found people are having with their silhoutte cameo 3s.
I had hit the arrow and changed to load media.
If your silhouette cameo 4 wont read registration marks for print and cut it is likely trying to read the grid lines on your cutting mat left.
Not aligning the mat in the proper position.
Failure to lock the roller bar.
During the loading process line up the mat with the small guide mark on the far left side of the machine rather than loading it justified to the left against the blade adjustment receptacle.
This is done by using the arrows on the machine.
If you are having issues with your device i hope this video can help.
If you are using a cameo the right hand pinch roller is not locked into place.