My S is partially broken, since I tried to use it with an F dock years back (not a good idea, pins are different).
But I don't recall ever having issues with a ZIF drive. again it's been some years for me now. Did you try this with a mechanical drive first, just to eliminate the ZIF SSD as a factor? Also what build are you using, the last stable one or a recent dev build? Reason why I ask is that I'm assuming the F/X/S's aren't really being developed for anymore so it's possible recent development builds aren't going to work - recent example and I edited another post of mine just now is flashwriter for the F/X which I cannot get to work anymore with recent builds.
Agreed btw on the F - a lot easier to work with. The X isn't bad either, just impossible to find in the US, I had to leverage Jauce some years back to get mine.