I have had this happen a couple of times with my set triggers over the years. In both cases, it was caused by the tightness of the lock plate screws, and was remedied by backing off the torque. Whether this was due to the lock mortise wood compressing over time, the effect of humidity on the wood, or simply my over tightening of the screws, the problem was permanently resolved by backing off on the tightness, just snugged finger tight, while still making sure the lock plate was secure and well mated to the barrel flat. As an aside, this level of torque on the lock plate screws can also effect the ease of ramrod removal with some locks, squeezing the portion of the rod tip that rests just behind the lock mortise. When I adjusted the trigger screw to address the trigger function, ramrod removal was effected when the lock screws were tightened too much. On any of my rifles, I will always check the trigger function and ramrod removal when replacing the lock. Not sure that this is the OP’s issue, but it may be worth a check.