I’ve struggled with the putting yips since the early 2000s. I found relief in the long putter, but relapsed after the anchoring ban. I’ve gone as far as putting right-handed in competition (I’m a lefty), so I consider myself an experienced expert on the topic, if not a guinea pig.
One thing that will help is to determine if your lead or trail hand is the culprit. A great way to do this is to putt with one hand from three feet. Test the trail hand first, then the lead. This may or may not reveal the source, but it’s a great starting point.
Odds are you’ll find that you putt worse when holding the handle with your lead hand only. As it has been for countless other golfers, a grip change is your best bet here.