Here’s something I learnt this week over on TB, and i wish i had known about this before, because I genuinely thought i had an issue with the truss rod in my P34 on a few occasions. The neck has never had an issue, but when i was setting it up i had a feeling the truss rod wasnt working 100%. Now i know it’s normal.
Not my post, just cut and pasted here for information.
Just be aware that with a dual-action truss rod there is a "dead-zone" or "neutral zone" that a lot of articles fail to mention.
That's when the truss rod is set perfectly flat in it's middle position, meaning there is no bow happening in either direction. There will be a couple of 2-3 turns where you will feel no resistance from the truss rod before it finally starts to grab again, and start going in the direction you are asking it to.
The first time I experienced this I was concern my truss rod was busted, but it will eventually get traction after a couple of turns in your desired direction and start to do its thing.