Twiddled your Flood gate?

They won't ever be quite rock solid, the whole point is that they do still move if you whack them, and IME they're not as firm as something like a DT.

If they're brand new they may need priming… trying cycling them through their travel a dozen times to get the compression damper working.

10mm sounds normal to me too.

I've a little issue with my SIDs in that the poplock (actually pushlock on mine) cable needs to be set exactly right to lock out. With too much cable it's still in the squidgy zone when locked out; with too little I can't push the pushlock far enough to lock because it hits the end stop. There's only a mm or two of leeway in this – and I've not noticed similar on my other RS forks.

So maybe you need to tighten the cable a little?

And does anyone know off hand if there's an adjustment I could make on mine to make the lock out kick in earlier in the rotation of poploc control?

If the twiddling doesn't sort it (it should, but may not) there isn't enough oil in the fork and you should have a chat with Fisher's about how to top it up.