The putting green is a very tempermental place. If we stand out there at 6 feet working on our mechanics and watch putt after putt miss we can really get crazy.
My advice is to work on your mechanics at home. Get the ball out of the equation. Work on your eyeline, your stroke path, and your hinge away from the putting green.
Then when you are at the putting green hit a bunch of 2 footers and 40 footers at first. At the end of the session hit 20 or so putts from different distances going through your routine.