The SW9VE has been 100% for many rounds after the changes were made, until just recently, when apparently the sear/striker interface developed a slippage problem. My SW9F has never failed with the same changes for many more rounds.
Yep, these machines occasionally develop malfunctions from use. Then it's fun and rewarding to fix them. And nowadays, making a liability-lawyer-constrained product better is also rewarding.
You asked input, and many of us suggested that the cause was the spring removal you did. You're clearly not accepting of that as a possibility and continue to ask the same question about what the issue could be. What could it hurt to just put the gun back to stock and see if it clears up the issue? It costs you some time, but perhaps reveals the cause. Your choice.