Happy Friday eve, SHWs and FCs! Many of my Silhouette clients have expressed difficulty cutting through the heat vinyl and permanent 651 vinyl. You are not alone, and it is not the vinyl 99% of the time. I am not claiming that Thermoflex is infallible, but review the site that I have attached to this message before believing that it is several different sheets of vinyl that others are using from the same exact "lot" or roll that you are using, yet they are not having any issues, but yours keeps messing up. My Cricut users are not expressing the same concerns which is why I believed this could be a Cameo 3 hiccup More than likely the site has the answers for you.
I hope this is helpful! I am learning the Silhouette myself and hope this mitigates the issues we are having in the studio with the Cameo 3 that has been added to our clients' use.