An elusive neutral, really a clutch disengagement problem, is most often caused by air in the hydraulic system. Any air in the system will be compressed and this will prevent the clutch plates from separating enough and allow them to touch and drag. It's this slight dragging that makes it difficult to slip into neutral while stopped. It also causes premature clutch wear.
The stock slave cylinder hydraulic ratio is designed to give a lot of leeway when it comes to bleeding, meaning you can have a lot of air trapped in the system and it will still work (at least partially), but that's why the pull effort is so high and why neutral can be hard to find when there's air in the system.
If you have not already done so, you can make bleeding much easier if you replace the banjo bolt at the master cylinder line connection with a bleeder-type banjo bolt. The master cylinder is where most of the air rises, gets trapped, and cannot be bled out (easily) using the bleed nipple down by the slave unit.
If you've installed a new clutch pack, drag-free operation requires that the metal plates be the correct thickness and absolutely flat, and that the overall height of the clutch pack not exceed specs.
On a bike with an original clutch and slave cylinder, a problem finding neutral will (almost always) be solved by bleeding air from the hydraulics.
For the rare case when purging air from the hydraulic system doesn't work, a clutch disengagement problem can be helped by increasing the clutch pushrod stroke distance.
The best way to do this is to change the clutch lever pull distance by changing the 4-position adjuster (early models don't have adjustable levers.) This is often necessary either after installing an aftermarket force-reduction clutch slave that (always) reduces clutch plate separation or after installing new clutch plates. There are four lever settings; where position 4 produces the least clutch plate separation, position 1 the most. This adjustment will also change the zone where clutch engagement begins.
Adjusting Master Cylinder Stroke Volume
Another way is to change the stroke volume (of hydraulic fluid) produced by the clutch master cylinder by adjusting the screw (covered by a hot-melt glue in later years) located between the clutch lever and the handlebar grip. Increasing the stroke volume will increase the clutch pushrod stroke distance and consequently the clutch plate separation.
You can increase the stroke volume by turning this screw IN about a half-turn. Mark its initial position for future reference. If you go too far, the master cylinder will not bleed back properly.
So, turn the adjustment screw OUT to move the clutch engagement point closer to the grip, and turn it IN to move it out. Remember to leave some play in the end of the lever after you're done, or you'll wear the clutch out prematurely.
A word of caution here. The reason that there is a factory seal over this adjustment screw is that it's not intended to be used as a service point for clutch adjustment. It's used by Brembo during final assembly to locate the clutch master cylinder piston in the proper position relative to a hole that allows the hydraulic fluid to return to the reservoir. Small changes here can make clutch function erratic and remove too much lever free-play.