I received my keyboard with the fingerprint sensor today. At first blush it didn't seem
to work as smoothly when dropping the surface (with keyboard attached) into the
Surface Docking station (originally for the Surface Pro 3). When I comparing the portion of the two keyboards that connect to the Surface, I found no noticeable difference (didn't use a micrometer or other measuring device - just eyeballing it).
I then noticed that when I connected the Surface to the keyboard, folded them together and pulled the keyboard up (parallel to the surface toward the edge opposite the edge that the keyboard hooks to) the magnetic strip that is between the keyboard proper
and the strip that has the connector moved slightly away from the connector edge. I then dropped the surface with the keyboard attached into the docking station, folded down the keyboard - Viola - everything fit and worked correctly.
This slight manipulation was un-necessary when using my original Surface Pro 3 keyboard, but it doesn't seem all that awkward to accomplish with the new keyboard prior to installing in the dock.
The increased ability to type (I'm a fairly rapid touch typist) without constant mistakes on the new keyboard is well worth the minor hassle of developing the habit of doing the above prior to putting the Surface / Keyboard in the dock.
Unless the QA on production allows considerably more variation between this portion of the two keyboards (with and without the fingerprint sensor), I would expect the manipulation I describe above would work with the other model keyboard as well (although
I'm not sure because I don't own the other model).
I was considering doing a little surgery with a razor blade on the portion of the keyboard that interferes with the docking - now - I don't feel the need.