Welcome to the forum,
If the shell isn't centered, it will catch. I've setup my presses with the spring shell holder keeper spring removed. This allows the shell holder to float a little and self center. The downside is that I need to be careful that the shell is centered. Maybe your keeper broke and is letting the shell holder float? If that is the case, a small rubber band will help keep the shell holder centered.
Another cause could be a shell holder that very loosely holds the shells, without being there, its tough to troubleshoot.
Does the ram appear to be moving straight up?
The ring you are seeing is from the seating stem, Have you cleaned your die lately? A buildup of lube on one side of the stem can cause a mark to appear.
Also, if you are using really old brass, it can get real hard and cause tighter seating, which in turn will require more force and you will start seeing a mark on your bullets.
If some is good and more is better, then too much is just right.
My mind is a raging torrent, flooded with rivulets of thought, cascading into a waterfall of creative alternatives