Use your palm or even better the silhouette scraper tool to press the media to the mat and check that is is stuck evenly throughout.
Silhouette mat moving around.
This can really prolong the life of your cutting mat.
So instead of always putting the end with the arrow into the machine turn it around and put the opposite end in that means the arrow will be pointing toward you.
To get more wear out of your cutting mat turn it around and use the bottom half too.
I actually purchased an a3 non brand cutting mat from ebay found the tacky to be just enough.
My silhouette 3 is still cutting in the wrong place up on the mat at the top left even though it is set for the 12 12 cutting mat in the silhouette studio.
Mat moving around sounds like the blue drop handle on the right is up or it is not places under the rollers quite right.
With newer mats this isn t usually an issue but with older mats you need to take an extra minute to make sure that it was adhered to the mat evenly everywhere not just in the middle.