Just to confirm, left is stiff. In this case you need a heavier tip. It might be that your center-shot and nock height are simply not adjusted perfectly. You could confirm this with a bit of paper tuning. You can try some bareshaft tuning to check spine, and walk-back tuning to check center-shot. If these prove to be correct, then I'd adjust my sight for the broadheads and only shoot those until hunting season is over.

Some bows have such poor nock travel, that even when tuned properly, the broadheads group away from the field tips, but usually not that far away unless that is from quite a distance from the target.